Reddit, what am I supposed to do with these pants?

I bought 2 pairs of levi 505 jeans at the store 1 week ago. I tried them on and while I was putting back the ones I didn't want, I mustve picked up the wrong pants. When I brought them home, I immediately ripped off the tags and hung them up. 2 days later I was invited to the movies. I went to go put on the pants and I noticed that they fit regularly around the waist but they got REALLY fat around the calf and ankle area. On the inside it says straight fit but they really fit like boot cuts. I can't return because the tags have been ripped off. How can I fix this? These pants are kind of on the expensive side.

tl;dr I brought the wrong pair of pants home & I ripped the tag off. They're straight leg but they fit like boot cut. How do I fix this??