[Lestat]

First, "terrible" is definitely not a term that I'd use to describe your pre-flop play. I think it's perfectly acceptable. However, since everyone seems all-too willing to call capping a no-brainer, I'll accept the role of devil's advocate:

I might just call, since you describe the button as loose and I assume he's not folding for another two very often. The reason I might play it this way is because I think this clearly is an instance where the pre-flop equity you lose can be more than made up for in post-flop deception. This is especially true if they are both loose AND aggressive. So on a bad flop, you'll lose less. A good flop, you'll win more. And with a great flop, you'll crush the begeesus out of them!