1. slang To speak truthfully and share everything one knows about something, especially a sensitive issue or a wrong one has committed. OK, spill your guts—I want to hear whatever you kids are plotting back there. I'm sorry, I didn't mean to just spill my guts like that. I hope I didn't overwhelm you.

2. slang To vomit violently and extensively. I've been spilling my guts all morning, so, no, I don't think I'll be in to work today.