Universal

If every person who watches little-watched 30 Rock bought a ticket to Baby Mama, the Tina Fey comedy would have, well, made a lot more money.

But in the weekend before the arrival of Iron Man, $18.3 million was enough to capture the top spot, per estimates compiled Sunday by Exhibitor Relations.

John Cho and Kal Penn's latest adventure in the munchies, Harold and Kumar Escape from Guantanamo Bay, opened in second. With a $14.6 million take, the sequel made almost as much in three days as 2004's Harold and Kumar Go to White Castle did during its entire run in theaters.

Baby Mama, meanwhile, marks the first time a comedy with a female lead has opened No. 1 since Kate Hudson and Matthew McConaughey's Fool's Gold in February.

A comedy with two female leads—Baby Mama costars Fey's former Saturday Night Live tag-team partner Amy Poehler—hasn't opened at No. 1 since, well…

Casual Sex? didn't open at No. 1, did it? (Um, no.)

The First Wives Club did, all the way back in 1996, but that starred three women (Diane Keaton, Bette Midler and Goldie Hawn), not two.

History-making or no, Baby Mama arguably makes Fey a bigger movie star than TV star. While her 30 Rock struggles to reach people other than critics and Emmy voters, her film career now boasts two No. 1 movies. (Mean Girls, from 2004, is the other.)

Then again, maybe 30 Rock's ratings aren't as small as they seem. If Fey's 30 Rock devotees (the show is averaging 6.5 million viewers) had each been a Baby Mama admission (at the 2008 average price of $7.14, per Lee's Movie Info), the comedy would have opened with an extremely fertile $46 million or so.

Guess we can't all be Iron Man.

Elsewhere:

• Last weekend's champ, The Forbidden Kingdom (third place, $11.2 million; $38.3 million overall) held up OK. Last weekend's also-ran, Forgetting Sarah Marshall (fourth place, $11 million; $35.1 million overall), held up even better.
• If only Al Pacino's 88 Minutes (eighth place, $3.6 million; $12.6 million overall) could generate as much heat as a Los Angeles Times column about Pacino's and Robert De Niro's squandered careers, at least one of those fellows' careers wouldn't be so squandered.
• Hugh Jackman plus Ewan McGregor plus a 2,001-theater launch added up to...next to nothing for Deception (10th place, $2.2 million).
• Expelled from the Top 10 were: Expelled: No Intelligence Allowed ($1.4 million; $5.3 million overall); Street Kings ($2.1 million; $23.7 million overall); and, Leatherheads ($1.8 million; $29.3 million overall), which, disappointment or no, is actually the biggest grossing movie of George Clooney's not exactly mainstream directing career.
• What in the world happened to Where in the World Is Osama Bin Laden ($58,945; $263,327 overall)?
• The French mystery-thriller Roman de Gare was the weekend's biggest little movie, debuting with $25,545 at two theaters.

Here's a recap of the top-grossing weekend films based on Friday-Sunday estimates compiled by Exhibitor Relations:

1. Baby Mama, $18.3 million
2. Harold and Kumar Escape from Guantanamo Bay, $14.8 million
3. The Forbidden Kingdom, $11.2 million
4. Forgetting Sarah Marshall, $11 million
5. Nim's Island, $4.5 million
6. Prom Night, $4.4 million
7. 21, $4 million
8. 88 Minutes, $3.6 million
9. Dr. Seuss' Horton Hears a Who!, $2.4 million
10. Deception, $2.2 million