Which one is bigger.

I had a thought just now while watching a video. Interesting idea for a meet with a stranger.
We both undress and compare our hard cocks - if his cock is bigger then I suck him, but if mine is bigger then he sucks me.
And the same applies to anal sex if it gets to that. The one with the smaller cock stays completely passive and also takes the bigger dick in his ass.
Will love to hear a comment if someone else thinks this can be hot too.