Actually your interpretation is the one that doesn't make sense. If I said why, I wouldn't have added the "for" at the end. For example, turn the sentence around.Originally Posted by Maniac©
What are you watching that crap for, Titanic is such a snoozefest.
vs.
Why are you watching that crap for, Titanic is such a snoozefest.
vs.
The better version of your interpretation:
Why are you watching that crap, Titanic is such a snoozefest.
So, now which one sounds better to you?