"yo 'si so 'si namo 'stu te" ei mantra pade
mukha-vadya kari' prabhu hasaya acaryere
yah asi—whatever You are; sah asi—so You are; namah astu te—I offer My respects unto You; ei mantra pade—chants this mantra; mukha-vadya kari'-making a sound within the mouth; prabhu—Lord Sri Caitanya Mahaprabhu; hasaya—causes to laugh; acaryere—Advaita Acarya.
Sri Caitanya Mahaprabhu would worship Advaita Acarya by chanting the mantra, "Whatever You are, You are-but I offer My respects unto You." In addition, the Lord would make some sounds within His mouth that would make Advaita Acarya laugh.
Link to this page: https://prabhupadabooks.com/cc/madhya/15/11