Here, is that Stotra composed by Adi-Shankara. It has 11 verses and gives such double meanings that it can be used to praise Lord Shiva and Lord Vishnu at the same time. It goes on praising 10 avatars of Lord Vishnu and Balarama avatar also in one side while in other side the same verses praises Lord Shiva (at the same time) due to it's double meaning nature.
महासोमकलाविलासं गामादरेणा अकलयन्न नादिम् |
मैनं महः किंचन दिव्यमङ्गीकुर्वन् विभूर्मे कुशलानि कुर्यात् || १
Vishnu: May the worshipful being Mahavishnu, who assumed the form of the Fish in the cosmic waters and restored to its proper place, the earth that had taken shape of a boat, bless me.
Shiva: May the great god Shiva who has the crescent moon on his forehead, who is wedded to Parvati, the daughter of Mena, and who is always associated with his Bull - grant me all that is auspicious.
यो मन्दरागं दधदादितेयान् सुधाभुजः स्मा अतनुते विषादी |
स्वामद्रिलोलोचितचारुमूर्ते कृपामपारां स भवान् विधत्ताम् || २
Vishnu: May that being (Mahavishnu), who assumed the form of a tortoise to support the churning rod of Mandara mountain and who thus helped the Devas, be gracious onto me.
Shiva: May I have the grace of that great god Shiva who has assumed a suitable form for his sportive manifestations on the mount Kailasa, who is adored by Mandara flowers, and who drank poison for the protection of the Devas.
उल्लासयन्यो महिमानमुच्चैः स्फुरद्वराहीशकलेवरो अभूत् |
तस्मै विदध्मः करयोरजस्रं सायन्तनाम्भोरुहसामरस्यम् || ३
Vishnu: I fold my hands in adoration of Him who incarnated as the great cosmic Boar and restored the earth to her position.
Shiva: I fold my hands in adoration of Him who shines with the great serpent Vasuki as his ornament and who sustains the devotee in his devotion.
समावहन् केसरितां वरां यः सुरद्विषत्कुञ्जरमाजधान |
प्रह्लादमुल्लासितमादधानं पञ्चाननं तं प्रणुमः पुराणम् || ४
Vishnu: I adore Mahavishnu, the Man-Lion, who destroyed Hiranyakashipu, the king of the Asuras, and was extremely solicitous about the welfare of Prahlada.
Shiva: I worship Him, who has five faces, who holds the Ganga in his hair, and who gladdened the hearts of the Devas by the destruction of Gajasura.
उदैत्तु बल्याहरणाभिलाषो यो वामनं हार्यजिनं वसानः |
तपांसि कान्तारहितो व्यतानीदाध्यो अवतादाश्रमिणामयं नः || ५
Vishnu: I prostrate before the great Vamana who performed austerities as a Brahmacharin with deer skin as his wearing cloth, who was without a consort, and who got back the worlds from the Asura, Bali.
Shiva: I salute lord Shiva who was desirous of getting the sacrificial offerings at Daksha-prajapati's yagnya, who lost his consort Sati, and who thenceforth performed austerities as a Brahmacharin, and who looks handsome.
येनाधिको घत्तरवारिणा अशु जितो अर्जुनः सङ्गररङ्गभूमौ |
नक्षत्रनाथस्फुरितेन तेन केनापि वयं सनाथाः || ६
Vishnu: May I receive the protection of Mahavishnu who incarnated himself as Parashurama, who had the brilliant form of a Brahmacharin, who was luminous like the moon, and who defeated Kartaviryaarjuna in battle.
Shiva: May I receive the protection of Shiva, who as a Kirata defeated Arjuna and who has the river Ganga and the disc of the moon in his matted locks.
विलासिना अलीकभवेन धाम्न्ना कामं द्विषन्तं स दशास्यमस्यन् |
देवो धरापत्यकुचोष्मसाक्षी देयादमन्दात्मसुखानुभूतिम् || ७
Vishnu: May Rama who with the prowess attained by the knowledge of numerous divine missiles, defeated Ravana, and who had Sita as his consort, bestow happiness upon me.
Shiva: May the great god Shiva who dispels all untruth by the brilliance of Truth-nature, and who destroyed Kamadeva (Cupid) having ten-pronged manifestations, and who had the daughter of the mountains as his consort, bestow happiness upon me.
उत्तालकेतुः स्थिरधर्ममूर्तिर्हलाहलस्विकरणोग्रकण्ठः |
स रोहिणी शानिशचुम्ब्यमाननिजोत्तमाङ्गे अवतु को अपि भूमा || ८
Vishnu: May Balarama, who has the palm tree as his standard, who is an embodiment of Eternal Dharma, who is forbidding on account of his fierce voice under the influence of liquor and the plough weapon on his shoulder, who is fondled by his father Vasudeva, and who is of indescribable brilliance - protect me.
Shiva: May Shiva who excels as a dancer, who is of the nature of Moksha-dharma, whose neck looks forbidding by the brilliance of the poison Halahala sticking to it, whose crown is kissed by the moon, and who is of indescribable brilliance - protect me.
विनायकेना अकलिताहितापं निषेदषोत्सङ्गभुवि प्रह्रष्यन् |
यः पूतनामोहक चित्तवृत्तिरव्यदसौ को अपि कलापभूषः || ९
Vishnu: May I receive the protection of Mahavishnu having by his side Garuda, who incites terror in the minds of serpents, and who in his Krishna-incarnation charmed even the mind of Putana, and who has a crown of peacock feathers adorning his head.
Shiva: May I be protected by the lord Shiva, in whose lap Vinayaka seated embracing him with his trunk, who has the Ganga on his crown, whose name is sanctifying, who presents himself in the minds of those who meditate on him, and who has the moon as his decoration.
पाठितकेतोर्जयिने प्रतीतसर्वज्ञ्यभावाय दयैकसीम्न्ने |
प्रायः क्रतु द्वेषकृतदराय बोधौकदाम्न्ने स्पृहयामि भूम्न्ने || १०
Vishnu: I worship the spiritual radiance manifested as Buddha, who was all-knowing, who was the conqueror of Mara, who was full of mercy, who was of the nature of Bodha (spiritual conciousness), and who was the adored of those who were opponents of Yagnyas.
Shiva: I worship that spiritual radiance Shiva, who is all-knowing, who is the destroyer of Cupid (Mara), who is full of mercy, who is all knowledge, and who is praised by those who destroyed the Yagnya of Daksha.
व्यतीत्य चेतोविषयं जनानां विध्योतमानाय तमोनिहन्त्रे |
भूम्न्ने सदावासकृताशयाय भूयांसि मे सन्तुतमां नमांसि || ११
Vishnu: I offer my salutations to Mahavishnu as Kalki-incarnation, who assumes a body of inconceivable splendour, who removes the world's darkness of ignorance by spiritual illumination, and whose advent is specially for destruction of evil ones and the protection of the good and the holy.
Shiva: I salute lord Shiva whose inconceivably holy form removes the world's ignorance by its spiritual splendour, and who resides ever in holy places like Kashi.