Come on, people.
Do you seriously need coaching on this kind of issue?
If it's offensive, you report it. The mods prolly haven't seen it- how many users are on this site? Don't you think that they have things to do other than minutely examine every avatar, thread and post for offensiveness?
If you've been here for any length of time (ahem) then you have probably seen Meta threads almost identical to this one dozens of times, with random posters accusing the mods of favoritism because someone is getting away with teh off3ns1v3 stuff and they haven't been smacked down yet!!!1!!eleventyone!
Every single time the answer is the same: REPORT IT.