For anyone who wants explicit tags:
Convert your files to .m4a (right click on album > create AAC version)
Download this:
http://www.mp3tag.de/en/download.html (the mac verison is a bit lower)
Drag the files to the program
Highlight all the songs
Press extended tags
Click this

In the FIELD box type ITUNESADIVSORY (it must be uppercase)
then in the value box type 1 (2 will give you clean tags)
Press OK (make sure you're not listening to any of the m4a files or it won't put the tags on)
When it's done, exit out and start listening to the tracks, the tags will show up!
Hope this helps!