I have the same kind of gas cap and just hold it in my off hand while I pump the gas. (I fuel up while sitting astride the bike.)

 

I make my wife hold it.

 

On top of the pump

 

Another vote for top o' the pump

 

I always take my right glove off then put it on the seat
then put the gas cap on my glove...

 

I always get off my bike while filling, so i put it on the the pump,

 

I always ( if they have it ) tear off a paper towel and put the cap chrome side down on it ,on top of the pump. There is often a ton of gunk on top of the pump and if I stand it on the tank side it may pick up dirt and crap that could end up in the tank.

 

On top of the pump!

 

I just put the rubber part of mine between my teeth. MakeS the coke I drink while driving go down better!

 

Never have understood people that fill up while sat on the bike - is there a reason to do this? I'd have thought from a safety perspective that it was safer to fill while off the bike - if you do spill gas you can move out of the way/mop it up quicker. Plus don't you risk overfilling while on the bike???