That famous wet shirt.

There in front of Lyme Hall is the famous piece of lakeside turf where Mr. Darcy emerged from the water in a clinging wet white shirt. He was not expecting that Elizabeth would suddenly appear and be moved by the spectacle.
This became one of the most viewed scenes in the BBC's adaptation of Jane Austen's Pride and Predjudice. It has been looked at on Google over 3.7 million times although the site does not tell us the percentage of viewings which were by females.

Firth later claimed that the original plan was that he would be naked but the both he and the BBC got cold feet. Looking at the lake this morning that does not surprise me.