When she says go deeper so you put your whole fucking testicles up her ass so far, it reaches her mouth. The act of “fullsend” generarally includes the act of fully cumming and creaming the entire insides of the femalecounterpart(s).
A statement generally said while 1. Trying to get your blackout friend to do some stupid shit or 2. Convince a group of people to do something that has potential to end very badly. Note that once a full send challenge is issued, it cannot be turned down.
"Hey man, let's drive down to San Franciscotonight"
"Bro, that's like a 4 hour drive"
"Full send"
"Fuck well I can't turn that down"