The sexless innkeeper is when you take what you think is a potential hookup home with you, and they fall asleep on your couch without hooking up. She or he only went home with you because you lived close by and they needed a place to crash for the night, therefore using your place only as an inn, making you its innkeeper. Defined by Barney on How I Met Your Mother.
"She slept there but you didn't sleep with her? You totally got used as the sexless innkeeper!"