(Speedbaged): when your sitting and fart and it rides up frontwards and hits your sac repeatedly. The longer you pass gas, the more your sac gets hit like a (speedbag).
"man I just let one go and (speedbaged) my sac. "
" a few things a womon can't do and one of them is give herself a (speedbag)"
"don't you hate when you (speedbag) yourself so hard, you almost drop to your knees