Wiktionary
sleeping policeman
n. (context British and Caribbean English idiomatic English) A speed bump.
Usage examples of "sleeping policeman".
If he wasn't at home when contacted, somebody'sgoing to be demoted to a sleeping policeman when I'vefinished with them.
Minogue looked at the sleeping policeman and wondered if he should wake him.
In an hour or two, the sleeping policeman would awaken and go straight to Bannister.