In general, fan service refers to scenes designed to excite or titillate the viewer. This can include scantily-clad outfits, cleavage shots, panty shots, nude scenes (shower scenes especially), etc. Some broader definitions also include things like cool mecha, big explosions, battle scenes, etc. Basically, if it has little plot-redeaming value, but makes the viewer sit up and take notice, it's probably fan service in one form or another.
In Evangelion, the episode preview for "Next time, service, service!"
Exclusive club for those in 6th and 7th grade. Only requirement to enter is to have the club's name written on one's body part, such as an arm or hand.
Johnny, join the Pen 15 club! Alls ya need to do is let me write Pen 15 on your arm.
Shittiest excuse for "music" ever created. Nobody knows why people even listen to it. Played at "parties," especially at parties thrown by some of my older cousins because they think they're "cool".
Rap? More like... CUH-rap!