I'm actually smack in the middle between 6" and 7", which lands me slightly above what I have read is the average in the part of the world I live in (northern Europe). Funny enough, the "small penis" humiliation is just bout the only thing that hasn't been interesting for me since I know I. do not have a particularly small penis.
But a variation of that has become an increasingly big part of the cuck dynamic me and my partner has. For us it has been mostly about me having problems with my erection (due to medication) and that has taken a big place in our dynamic, partly due to me letting it happen.
So while I enjoy her commenting on my worthless penis and how she gets so much satisfaction from other guys (every now and then referring to them as real men), it has everything to do with keeping an erection and much less to do with me being "small".