get it off with someone—(sl.) have sex with a person (also: get it on with someone):
- She said all he wanted was to get it off with just anybody.
get off with someone—(coll.)
1. move aside with a person to discuss smth.:
- We got off with the client and explained the offer a little better.
2. become friendly with one of the opposite sex:
- What fun it would be if one of us could get off with him.
Note: The expression does not correlate in meaning with the phrase get off with you—(exclam.)
1. is used to rudely tell a person to go away (and stop being annoying ):
- Get off with you! I’m trying to work.
2. is used to emphatically express disbelief:
- Get off with you! Do you think I’d believe a story like that?