Not technically illegal, try it at home!
UPDATE: I have been informed that this is in fact illegal and that you should not try it at home.
Gun Ownership #1
Ms.Gun: ...So you're saying that would be a crime
Ms.ExplainTheLaw: Right - it's called armed robbery
Ms.ExplainTheLaw: As a general rule, you can't force people do to things they don't want to do at gun point
Ms.Gun: Ah! That's it!
[A crowded restaurant]
Ms.Gun: EVERYONE GO ABOUT YOUR BUSINESS AS USUAL OR I SWEAR TO GOD I'LL EXECUTE EVERY LAST ONE OF YOU