a rude phrase meaning to be very serious and easily offended, and always want rules to be obeyed: She has a stick up her arse and likes lecturing people.

What does having a stick up mean?

(Entry 1 of 2) : a robbery at gunpoint : holdup. stick up.

Why is it called a stick up?

also stickup, 1857, "a stand-up collar," from verbal phrase (attested from early 15c.), from stick (v.) + up (adv.). The verbal phrase in the sense of "rob someone at gunpoint" is from 1846, hence the noun in this sense (1887).