1) To remove the fun from a situation (especially a competitive game.)
2) Someone who disappears for the night with a member of the opposite sex and then refuses to share the sordid details of the encounter with their friends
Similar to cliffhanger in a TV show. When you end a kinky chat session or erotic role play to pick it up later, but it leaves you sexually aroused, because you did not "finish"
I had some real sweet erp with Jil last night, but it got late, so she left me with a cliffboner