I don't quite understand.. are you trying to imply that being bigger means you can take a bigger cock than slim men? Now I'm no expert, but I can't imagine that your weight or height affects your sphincter muscle - does it?
I'm all confuzzled now! Have I completely misunderstood? It wouldn't be the first time! lol
PS - I'm a big girl and believe me, I don't care how small the sausage is, it's still not gonna happen - OUCH! lol