I don't know what fist bug you mean, but erhm heres one.
Don't know if it still works lmao xD
Equip your weapon, 3th slot usually.
Then Press the R button, and hold it.
After that Scroll above to equip Fist.(Keep holding the R button ;P)
Then Scroll To equip Ur 3th slot weapon again.
When you shoot other people will think ur fisting.
You can't Roll, and you will have to keep the button R down =P
It goes like this, Doesn't it? : o