Like the t-shirt you had to have but only wore twice and now you don't like it.
Or the time (more than one in my case) that you spent more than a 100 bucks at the bar.
Or spending money on lunches that are 15 bucks when you can easily bring one from home. I am not that bad with this, but there are times when I spend 6 bucks on a useless jugo juice.
I am not to pleased now that I look back. I could have saved a few extra thousand bucks. Money that could really be usefull right now.