Hysterical Video of Wedding Proposal When Ring Goes Overboard

This is hysterical ... a wedding proposal on a boat goes horribly wrong because the would-be fiance's wingman has a TERRIBLE throwing arm!!!

We don't know their names or exactly where they were, but it doesn't matter. The ring, inside the ring box, goes in the drink and a guy -- presumably the thrower -- jumps in to retrieve it.

We don't know if he got the ring back, but you gotta say ... it's a memorable proposal. We're assuming she said yes, even sans bling.

And, this is funny ... an NFL meme page posted the video with the caption, "When you ask Mitch Trubisky to help you with your proposal ..."