How to get a mustard stain out of the pants I am wearing?

[Pocket Trips]

I had a sandwich with mustard on it for lunch and of course i got mustard on my pants. I am planning on wearing these pants to AC tonight and possibly going to a club. I have tried soap and water in the bathroom here 3 times now and it just is not getting any better. They are black pants and the mustard is faded now a bit after the 3 attempts at soap and water and now looks like a damn slooge stain by my crotch. At least before I just looked like a slob, now I look like a damn perv ( which i am but this is irrelevant.)