Airheadap, well yeah, I'm really bad at things like that.. personally I would NEVER ask someone out.. Gosh, so humiliating.. NEVER. So how did I solve the problem? I told the whole school which resulted in this person called me really bad things.. Hm. But then again, I'm a girl who fell in love with a guy so.. I can guess your situation would be different.
So, that's what NOT to do.. haha. You could just say you love them.. who knows.. better to regret something you did than something you didn't do... and of course if they freak out about the SMS (this only works with SMS or email or somethig) you simply tell them that it wasn't you who sent the message, it was your sister/brother/dog, or something.