"You've got something ___" is a phrase that you use to tell people that there is food or another substance somewhere on their bodies that it doesn't belong. For example:
Hey, you've got something on your lip.
You've got something in your hair.
"You've got something ___" is similar to "you have something ___". Both are OK for normal conversation, but I would usually say "got something". "Have something" sounds just a little more formal.