Best definition
Your Grandpap can’t fap
The action in which an individual in a deathly situation when insulted with “your granny tranny” takes the last insult

that also ends their opponents life.If you were to survive the “your granny tranny” insult, this insult would leave you, and your opponent, and their family in an instant death.

Bob: Your mom gay!

Jim: Your dad lesbian!

Bob: You leave me no choice, Jim

Jim: No! Don’t do it!

Bob: your granny tranny

*Jim collapses from cardiac arrest*

Jim’s Final words: Your Grandpap can’t fap …

*Bob and his whole entire family dies of spontaneous combustion*