i'm selling a amp on ebay. someone ask a question he say: (does this amp even sir?) what does sir mean.

 

My best guess is a typo.

 

I'm with Pure Adrenaline... Probably a typo, but what kind of amp is it?
Perhaps the interested buyer knows a little bit about the product you're selling and SIR is an abbreviation for something that the amp does/can do.

....I'm grasping at straws here, but you never know.