Man, these are hilarious!

AC/DC - Big Balls in my pants

Jizz in my pants



o wait...

Lollipop in my pants ^_^

On a Pale Horse in My Pants

Heartbreaker in my pants

Forever Young in my pants

Temptation in My Pants

I will find a way in my pants

Tom Sawyer in My Pants

(Matchbox 20)

How Far We've Come in my pants

Hadouken!
Spend Your Life In My Pants
Play The Night In My Pants
What She Did In My Pants
Liquid Lives In My Pants (ew lol)
Get Smashed Gate Crash In My Pants

System Of A Down
F*** The System In My Pants
She's Like Heroin In My Pants
Holy Mountains In My Pants

Jimi Hendrix

Fire in my pants

Korn

Daddy in my pants

o-o
lol

More random selections with pity commentary:

I Wear No Pants in my pants.  (That would, after-all, be redundant.)
Getting Directions in my pants. (They do say communication is the key to enjoyment.)
Happiness is a Warm Gun in my pants. ( )
I Don't Think You Know Me in my pants (From the, "Boy, you look totally different with clothes on" department.)
Cheek to Cheek in my pants (Somehow that's not nearly as romantic as the original.)
The Leaves Be Green in my pants (  )

GnR - Ain't it Fun in my pants

I was reading some of these to my sister because we were getting a kick out of some of them, and she said this game is similar to the fortune cookie game where you add "in bed" after your fortune. For example "you are very wise in bed" LOL
Try it next time you go out for Chinese.

Tool

Prison Sex in my pants

Korn

Beg for Me in my pants

MSI

2 hookers and an 8 ball in my pants

Jimmy Dean

Big Bad John in my pants

Pantera - The Art Of Shredding In My Pants

Anthrax - Caught In A Mosh In My Pants

The Beatles - Norwegian Wood In My Pants

Dancing with the Lion in My Pants

The Cure
-- Boy's Don't Cry In MY Pants 

Beach Boys

Fun,fun,fun in my pants

Damien Rice

Cold Water in My Pants