How do I stop myself from blurting out rude comments? ?

So, I'm kind of popular. And kind of rule the skl. And sort of mean. I know, I know , I ADMIT IT. LOL. But when i see some freaky girl or guy wearing ridiculous clothes or doing something weird , i blurt out the RUDEST thing my mind can think of. For example, last week some girl looked like she hadn't looked in the mirror for a long time so i just yelled out, in front of everyone, " What a freak show!!! " She turned around to see who said it but i quickly ran away. I felt soooo bad the entire day. I do alot of these things. One day, at the mall, a highschool couple was making out in abercrombie. And i just yelled, " Get a room!" They were REALLY angry. I mean, i make out in public but how come I don't approve of other ppl doing it? How do i stop??? I'm really mad at myself.