I was once in a fight on new year's eve on the way back to a friend's house. His gf was with me and she called him up in a panic (he was at home preparing for revellers to arrive). He leapt in his car and was coming to pick her (and me, I hope) up only to be immediately pulled over by the police, who naturally make a big deal of enforcing the drink drive laws on NYE.

When he tested positive I felt very guilty indeed. When he was taken to the police station, retested, and found to be a nanogram below the limit, I was very very pleased indeed (notwithstanding the black eye spreading over my rather drunk face).