Is racking the slide by one's teeth a common technique?

No, I don't rhink so. Your teeth would hurt.
If your other hand is occupied, then the methods that's make sense is racking your pistol using other bodyparts that can do a gripping motion, just like your armpit, the back of your elbow, the back of your knee, or even in between your thighs (that include using your crotch) if you want some special "feel".

hungkok2007 said:
Is racking the slide by one's teeth a common technique?

It is in same caste with pulling grenade pin with your teeth. It might look cool but trying it and pulling your teeth out makes you look very uncool.

makkun said:
other bodyparts that can do a gripping motion, just like your armpit, the back of your elbow, the back of your knee, or even in between your thighs

Or, in the case of this character, possibly in the cleavage.

Thanks for the heads-up.

What the hell did she do to her vest?

ok is it me or those she look like Kagura from azumanga daioh