Excuses for losing

He shouldn't have played on in a lost position

My perpetual check didn’t last very long

I played a knight sacrifice, but he took my queen instead

I studied How to Beat Bobby Fischer and was unprepared for other opponents

I had a big advantage when my opponent found a lucky checkmate

All my pieces were optimally placed, unfortunately it was my turn to move

I tried the King’s Gambit, but became demoralised when I went a pawn down

It was a theoretical draw, but my opponent didn't realise this

His knight wasn’t pinned after all

One of the Polgar sisters said that she has never defeated a man who (claimed to be) in full health.

another excuse I hear all the time.
I came up with a brilliant combination but I didn't do it in the right move order.

LOL!