Our son Yadunandana (4.5 yrs) came one day after the school (run by devotees) and asked why he had to say "excuse me" after belching. We can hear Srila Prabhupada sometimes making heavy noises during the class and we have seen many sanyassis pass air or belch and say nothing. Could you please explain how one should behave according to vaisnava ettiquete when one happens to burp, belch or spit etc. while with others?