It's also a lot of fun.
You've obviously never met the right pair. :-)
Note that ESRB ratings change over time. Quite a few Virtual Console and Xbox Live Arcade re-releases have been rated E10 even though the original releases (with the exact same content) being rated T.
Also, the ESRB listing for "Duke Nukem" is for the Game Boy Color game, which is a completely different game.
duke 1 the page now shows a teen rating
duke 2 rated E now
Duke Nukem 3D: Atomic Edition rated m
Duke Nukem: Manhattan Project rated m
Duke Nukem 3D for Xbox LIVE Arcade rated m
the game was very controversial when it came out seeing that you go through strip clubs and adult video stores.
Although to be honest, the swearing is probably stuff you have already heard and the tits are rare and pixelated, nothing to get excited about. The mature content in this game is actually pretty laughable by today's standards.