Cheap thrills is recieving pleasure or "thrill" and spending very little or no money at all on it. To gain more understanding listen to Cheap thrills by Sia.
The term could also be used as another word for a free bootycall
Jessica: I'm a bit low on cash.
Jord: No problem, cheap thrills this weekend?
Jessica: Yeah we don't need cash to have a good time.
Brandon: You up for a cheap thrill?
Natasha: Boy, I ain't about that cheap hoe
life. You better be paying for this.