After he nuts in your mouth, you don't swallow and french kiss him. Therefore the nut is transferred from your mouth into his. Like a mamma bird feeding it's young.
When you hold the joint up to your friends mouth for them to smoke
“Yo, my homie, home dog, homeslicecicle Mama-birding me dat joint yesterday.”
“Is that when they hold the bunt for you?”
“Yeah it got me feeling homosexual”