I stroked a few guys in the course of my life. The first one was my cousin's boyfriend. When they know you are average or below average, some big dick guys will always try to make it indirectly a subject or put this unequal situation into evidence. I think in Brazil there are more ways to know if a guy is hung or not because of our beach clothing protocols and because girls talk about it more shamelessly. I also think jerk off sessions and comparisons are more frequent here than elsewhere.
Anw, this is not something I need to do all the time, but I enjoy doing sometimes.
People wonder about humiliation. Yes, there is a degree of that. You will have to give up any pretense of being the "alfa male" around the dude whose dick is bigger than yours and you have admired. But most of the time it's worth it because this is simply a private and not a public affair. It feels good to befriend a big dick guy at this level. After all, he wouldn't do it with anyone - he chose you. Of course, having a 14cm dick, I will only anonymously admit that.
If you are a guy, you are 100% sure you're not interested in sex with dudes, and, therefore, you are not paralysed by homophobia, this is something fun to be done in front of the mirror.