When you perform a sexual favor and do not recieve one in return. The person in question automatically calls "no tag backs" by obstaining from reciprocating your favor.
Mike: "Hey man, did you go home with Jane last night?"
Stan: "Yeah. I went down on her for a bit, but she didn't return the favor."
Mike: "What? She called no tag-backs? That's lame."
Stan: "Pretty much. She said 'thanks,' then went to sleep."
The ultimate in no tags back. Negates any previous tags back, and ultimately allows the sayer of "infinity no tags back" to win at tag.
Loser: Hey, that's not fair, Jimmy, I called no tags back!
Jimmy: Fuck you bitch my name ain' Jimmy its J to the I aughts to fuck you up and oh wait I just did by taging you and callin "infinity no tags back".
Loser: Thanks for clarifying.