This happened when I was in a club the other day. I was just chillin at the bar minding my own business when this obnoxious drunk fat girl started slobbering all over me, then her bf came over and accuses me of hitting on his mrs, now this guy was big, you could tell he did some serious weightlifting, must have had a good 100lbs on me and I just laughed and told him: "I wouldn't touch her with a barge pole, she's fat, you're ugly, i'm neither, I could pick up better looking chicks at a science fair, now get lost you meat head".
He didn't appreciate this and threw a left hook, I ducked, landed too kidney shots and when he turned around I caught him in a clinch landing three knees and an elbow, he looked dazed and was nursing his bloody nose, I was in a real bad mood earlier though so I took him with a single leg takedown and side mount, then proceeded to rain down one hammerfist after another. That let off all my steam and he was just laying there holding his face and I was just 'ha, where's your dbol now bitch?' and got the hell out of there before the bouncers got me (this all happened over the course of about 15 seconds).
And something similar has happened before, there was this arrogant bastard back in school, he was sprinter and considerably bigger than me, and kicked off with me once, but I wasn't in no mood to take shit from anyone so I just caught him with a scissor takedown and heel hook. He was lucky I didn't break his ankle. And when he was rolling around in agony I laughed when I realised his gf and lackey were watching
Man I know having muscle looks good, but what's the point if you're still going to get you ass handed to you buy a trained guy less than half your size.