The film stars Ashton Kutcher and Seann William Scott as two best friends who find themselves unable to remember where they parked their vehicle after a night of recklessness, ultimately uncovering a conspiracy that threatens the universe.

The two also learn they have almost been fired from their pizza delivery jobs, and they find the cabinets in their kitchen are full of containers of pudding.

They emerge from their home to find Jesse's car missing (leading to the titular question) and with it their girlfriends' first-anniversary presents.

Because the girls have promised them a "special treat", which Jesse and Chester take to mean sexual intercourse, the men desperately begin retracing their steps in an attempt to discover where they left the car.

Along the way, they encounter a transgender stripper, a belligerent speaker box operator at a Chinese restaurant's drive-through, two tattoos they discover on each other's backs, UFO cultists led by Zoltan (who later hold the twins hostage), a Cantonese-speaking Chinese tailor, the Zen-minded Nelson and his cannabis-loving dog Jackal, beautiful Christie Boner, her aggressive jock boyfriend Tommy and his friends, two hard-nosed police detectives, and a reclusive French ostrich farmer named Pierre.

The search for both the car and the Transfunctioner leads Jesse and Chester to the local arcade and mini-golf course, Captain Stu's Space-O-Rama.

Once inside, they encounter Zoltan and his cultists who give them Wilma and Wanda in exchange for a toy that Jesse and Chester try to pass off as the Transfunctioner.

The two correctly choose the Norwegian men after they successfully answer their question about the previous night by stating they got a hole-in-one at the 18th hole at the arcade's miniature golf park and won a lifetime supply of pudding.

Enraged, the five alien women merge into a beautiful 50-foot giantess clad in a purple bra and matching miniskirt.

Chester suddenly remembers a nature show from earlier in the day, with chimpanzees using sticks to gather food through small holes, and applies the same logic with a straw to push the recessed button, destroying the alien.

The Chicago Tribune said: "At the end of 83 unmerciful minutes, audiences will be exclaiming, 'Dude, I can't believe I sat through that movie!?'"

and the New York Post said that it was: "An almost chuckle-free mess, so amateurish and lame that the cast often has that embarrassed look you see on dogs given ridiculous haircuts.

[15] After a Twitter campaign to encourage the "real" Zoltan to appear at a game, Hal Sparks flew to Pittsburgh on July 25, 2012, to throw out the ceremonial first pitch, and was on hand to see the Pirates win 3–2 over his hometown team, the Chicago Cubs.