I guess I showed her!

[wowenglish1]

I would like to know the meaning of the next sentence.
I guess I showed her!

 

[Barb_D]

The expression "That'll show you" or in this case, "I guess I showed her" means "This will demonstrate who is smarter, stronger, right, etc."

The humor is that the boss thinks he won the argument, but she spend a lot of his money to buy herself something, so she really won.