At least we know your not a **** boy :p

Any normal human being would furrow their brow, smirk, and say, "Why, thank you. I was thinking of going for rhombus today but decided on this at the last second."

It's ok OP. Just have to work on flirting while your working on those nice biceps ;)

They say steroids shrink your balls.

if you can't think of a witty response, just say nothing. Some women like the strong silent type, just to be safe don't say anything for the first 5 years of marriage.

You really should stand in the corner and reflect on what you done. For shame.

Sounds a bit like social anxiety, but I could just be projecting. I've been there before, OP. Somebody says something nice to me, and I sort of awkwardly smile and mumble "thank you," and then shuffle off. Then I realize later I should have tried being friendly back and curse myself for not doing so.

Either you had to much to drink or you were just a little shy.

I honestly believe that direct complements are quite difficult to deal with sometimes. Most of us never get a direct complement beyond the basic, you look good. And usually that is only from friends, so from a stranger it is usually rare (maybe I'm wrong, but it's my experience) and we are unfamiliar with how to react. Society needs to allow us to complement strangers more often.

Mission failed, we'll get em' next time.