What's the most embarrassing/awkward thing you've ever done?

I was at a pub a few years ago, there to meet a girl I had just started seeing and her friends who I hadn't met. I walked in, spotted her with her friends and she had her back to me. For some reason I decided it would be a fantastic idea to surprise her/show off (I don't know why I thought this would be showing off) by walking up behind her, putting my hands over her eyes and saying "boo".

So I did just that - I even half hugged her and pulled her toward me as I did it.

It wasn't her. It was a stranger, her friends gave me the weirdest look and when she turned around she was so creeped out. I left and texted the girl I was meant to be meeting to meet at a different place. Haven't been back to that pub since.