The Los Angeles Times made a list of 8 "summer sleepers," in anticipation of Knocked Up being the next one:
1) 40 Year-Old Virgin (8/19/05)
2) Wedding Crashers (7/1505)
3) Mean Girls (4/30/04)
4) My Big Fat Greek Wedding (4/19/02)
5) The Sixth Sense (8/6/99)
6) There's Something About Mary (7/15/98)
7) Forrest Gump (7/6/94)
8) Ghost (7/13/90)
I'm not going to suggest additions but I did double-check to see if these movies were really unexpected hits. For example, Mean Girls was the widest release on the weekend it opened and the 4th widest release in April. Calling Mean Girls one of the greatest summer sleepers of all time is like calling Disturbia the same because both had no real competition. With the MTV Movie Awards coming up tomorrow, it also reminds me that Shia LaBeouf was once just "That curly-haired kid from Holes with the thing for Lindsay Lohan."
Ghost is the one choice that really enlightened me. It was the number 2 grossing movie of 1990 — behind the juggernaut Home Alone — but had the 71st biggest opening. Of the 70 opening wider, I can remember seeing about 20 in theaters, and of the other 154 below it, I saw but one (Fantasia) in theaters and can at least recognize only 5 others. Point being, Ghost really did come out of nowhere, and, furthermore, I'm probably not going to remember Mr Brooks in 2024. As is, I've already forgotten everything else Kevin Costner did between and Thirteen Days and The Guardian.
 Although it seems paradoxical (if not quite oxy-moronic), I can't convince myself that something shouldn't still be a sleeper if everyone picks it to be, and for that I blame Bill Simmons
 Behind 13 Going on 30, Kill Bill vol. 2 and Home on the Range, the last of which I really do still plan to review.
 Disturbia was acutally this April's widest release. 2, 3, & 4 were Are We Done Yet?, Firehouse Dog[!], and Next.
 /'Even Stevens' which I assure you I never watched. Really. ¬_¬
 Just My Luck, Prairie Home Companion & Georgia Rule COMBINED made less than 'Disturbia.' Let's not even speculate on Surf's Up, Transformers, and Indy freakin-4. Considering how things have been going for him, I'm surprised LaBeouf doesn't have Justin Long's role in Live Free or Die Hard to boot.
 Mo Better Blues, House Party, Dances with Wolves, The Freshman, Green Card, and Edward Scissor Hands.
 Ooooh...stylin on Kevin Costner? I'm mad edgy, manky.