Wallace and Pants Finding Pants Toy Pants Monsters Pants Does it show I've been to see Finding Nemo, and am in a rather Pixar-y mood? OK, aardman too...
There's the movie, the Incredible Shrinking Pants and its rather less successful spin-off, The Incredible Staying-Exactly-The-Same-Size Pants which was a disastrous movie, but the idea was bought by Marvel Comics and following some character development resurfaced as The Incredible Hulk series.