Agrapuja in Hinduism is the social custom of offering respect to a great person. The word literally means worship of the elder. It refers to the practice of paying tribute to the most illustrious person of the age in a large gathering of eminent persons who are invited for a special occasion.
It is said in the Mahabharata that if any eminent scholar, king, relative, performer of yajnas, graduate or favorite friend happens to visit you after a year, he should be honored with ritual offerings and welcomed. If many great men are present, the most eminent should be honored first (the Mahabharata, Sabha Parva. XXXVI.24)
The famous agrapuja was performed by Yudhisthira, the eldest of the Pandava brothers in the Mahabharata. After establishing Indraprastha as the capital of his kingdom, he was advised to perform Rajasuya Yajna, to establish his supremacy over other kings.
While performing yajna, agrapurusha is chosen and honored first before honoring every other invitee.
Yudhisthira asked the elder most Kaurava, his grandsire Bhishma, to guide him in the choice of agrapurusha or the most eminent personality present on the occasion. Bhishma suggested the name of Krishna.
Yudhisthira worshipped the feet of Krishna and garlanded him as the most eminent contemporary personality. The enemies of Krishna, however, could not reconcile themselves to his choice.
The first among the kings to protest was Shishupala, the king of Cedi. He got up and protested vehemently, showering abuses on Bhishma, Pandavas and Krishna himself. Later Krishna killed Shishupala with his Sudarshana Chakra.