@aznrockstar thank you so much! I'd given up hope!🙇

Hwy @lololulu19, thank you for your guess. Didn't get you clearly, whose logins are it?

#2 and #3 have nice butts, especially #2

Who are these guys?

I once had a roommate (never had sex with him), whose ass was like a bag of rocks. An ass is comprised of muscle and fat. A female's ass is primarily fat and can be gigantic. A male's ass has a lot more muscle and doesn't get as big because it's not fatty (likewise women have big fat tits).
If someone has no ass (no muscle and fat) then they are underweight and/or have very little muscle.