Checkmate

Flight Attendant (FA): Sir, the flight is totally full. Can you pit you backpack under the seat in front of you rather than in the overhead?

Me: Why?

FA: So this who brought roll aboards can use the space.

Me: I checked my roll aboard so I'd have room to put my one carrying item, which by your policy I'm allowed, in the overhead. I plan on putting my feet under the seat in front of me.

FA: If you can't or won't put it under your seat I'll have to check it for you.

Me: If you do that then I'm afraid that I'd be so worried about it that I won't be able to carry out exit row duties, and you'll have to reseat me on this FULL plane.

Bag stayed in the overhead. I kept my seat too!

Checkmate! I win!

IMHO, Any roll aboard larger than a hat-box should be checked. It's getting both ridiculous and dangerous having all that crap up there.