Dumb stuff you've done and can't stop criticizing yourself about?

I don't get out much so I usually make a lot of stupid mistakes, examples include: Taking the wrong bus, using the wrong end of a bank card when trying to pay for stuff, and so on. So while I head back home I always have that little voice telling me how stupid that was and sometimes it lasts all night. Anyways what kind of dumb things have you done and any advise on how to stop it from haunting you for several hours after wards?