l was watching Who is your Caddy n the guy messed up n said ''OH! Mulligan!'' Then l also saw it in FamilyGuy when Peter was playing golf n missed the ball he said ''Mulligan!''. What does that mean? What does it have to do wit golf?

It means you take a redo on the shot

when sumone says mulligan in gulf it meens that they wanna ''redo'' or ''another try''

mulligan=redo
not allowed in tournament golf nor when your playing for money, but when your playing with friends theyll usually let you take another shot without a penalty if for example you hit a ball into a lake

some people refer to only a repeated tee shot as a mulligan, but you can say mulligan on a fairway shot and people will know what you mean

its simple mean to take another (redo) shot without taken a penalty for the first shot.

Yuppers it means that shot does not count, ask any living President or Governor

A 'Mulligan' can only be requested on the 1st tee. A mulligan is usually a wayward tee shot that you can hit again only on the 1st tee, as up to that point of hitting a sucessful drive, you are deemed not to have started your 'scoring' round.
It is only however a give between golfing friends having a freindly game of golf.

As others have said, mulligan is to take a shot over without penalty. Strickly against the rules of golf but may be allowed in a very ''casual'' round.
Supposed to came from the term ''maul it again''.

A mulligan is basically a free do-over.