two defs I know of:
a). tellin' a teenage girl to be good and that shes got no better friend than her mamma.
b). insult: when someone got stronger facts in debate you have no other choice than to mention this, if the person is not your homie and you r ready for real insult you can put a anymal in front of it, (my dog got desease cause he love yo mamma)
a) girl: I am 13 and I can do whatever I want!
advice: Love yo mamma
b)homie: So u say you heaven't smoke all the shit.
you: love yo mamma