As someone who's had this happen to them before - guys, please don't. No matter how cute or romantic you think it'll be, before you try that awesome move you saw in a movie, just ask yourself what's the worst that could happen? Then ask yourself how strong and coordinated you are. Then ask yourself how coordinated your girlfriend is. Once you've done all that, then - and only then - may you proceed, at your own risk, with the utmost care and caution.