This is disturbing. I truly hope you guys are joking.
My guess is most the people who are joking are doing so so that people like you don't take them seriously... Even though they may be serious. I'm sure some people are really just joking though. But I'm sure a lot of them are serious, too..
To be fair, "Sexy" is kind of a flexible word. Sure, most people interpret it as "arousing", but it can also be used for something that's attractive or svelte in the general sense ("The car had a sleek, sexy design"). Of course, when you bring up their posteriors, all bets are off, heh.
I'll post my favorites later. It's so hard to pick!