Weird tasting Orange Juice?

Sounds like it fermented. Just because it's in the fridge doesn't mean it won't go bad. You need to drink it after I'd say 5 to 7 days after opening and make sure its refridgerated the whole time and not left on the counter for a few hours and put back in the fridge. If you leave apple juice in a closed container sitting on the counter for about a day and open it, smell it, it smells like alcohol.