Robbed by bad grammar: Stick up vs. stickup

Don’t let these two words hold up your writing!

Stickup is a noun meaning a robbery at gunpoint, as in That convenience store has seen more stickups this year than any other in New York City.

Stick up is a verb in which a person raises his or her hands straight up in the air, which is what police will ask a robber to do when caught, as in “Stick up your hands!” the Los Angeles policeman shouted.