I don't know if this is at all useful to you guys as it seems more appropriate in the context of a relationship, but I think you could make it work in a less romantic context.

I recently realized that I give weird and somewhat memorable compliments. They tend to be blatantly offensive on the surface until I explain it. A recent interaction with my girlfriend:

blah blah conversation is getting kind of deep and sappy

Me: If I only had a few hours left on this planet <pause> there isn't a hope in hell I would spend them with you.

Her: You're such a jerk! *punch*

Me: Yeah, time goes by waaaaaay to fast when I'm with you. If I only had a few more hours left I'd drag that shit out. Find the most obnoxious person possible and chill with them until I wanted to kill myself.

Her: *hug* you're suck a dick :3

Me: Thanks babe. Now go home, I don't want Monday to be here already.

I think the trick is to be sappy just long enough for her to know that you're capable of being romantic, then go back to being cocky and funny like it never happened.