Like many Nintendo games in the past, small, subtle changes were made to suit the American audience. This usually included the removal of sexual and religious stuff, and Link's Awakening was no different.
First, Link's Awakening originally came out on Game Boy 1993 (in Europe) before the DX version was released on Game Boy Colour around five years later. Here's the interesting stuff:
There is a mermaid who lost her necklace in the game. Well, at least in the US version and a few language versions in Europe (the English one for example) that is. In the Japanese version and in most European language versions, she lost her bra (LOL). This was changed in ALL European language versions for the DX game - now she lost her necklace. However, in the Japanese DX version, she still losts her bra. Leave it to the Japanese to have no problems with sexual innuendo.
Hackers have implemented the original text and actions into the DX version, which can be seen here:
As you can see, there's also a naked hippo with huge boobs who tries to cover herself when Link gets close. In the western version, she has no towel but no boobs either, she just looks like a plain ol' hippo. The idea is that the artist in the same room paints a nude picture, but not in the western version.