booty call
1. An overture or invitation for a purely sexual interaction. This phrase is not limited to phone calls, despite its wording. Come on, if he's texting you at 1 AM, it's definitely a booty call.
2. One who is purely a sexual partner, often of convenience, rather than a romantic partner. I'm looking for a serious relationship now, so I refuse to be your booty call anymore—lose my number.
3. Strong sexual desire or arousal. He doesn't want to date you, he just reaches out when he feels the booty call.