Nothing is going to happen.. Celebrex is an NSAID, which are used for the minor treatment of pain. You shouldn't take more than 400mg in a 24-hour time period, so I hope you definitely know how much you took or didn't go too much over the daily limit. You'll probably experience minor symptoms such as a stomachache, nausea, possible vomiting at the most.
Why did you take eight year old Celebrex anyways, may I ask? Anti-inflammatory drugs aren't the best for your stomach, so try to eat a light meal. There isn't any significant interaction between Celebrex and methamphetamine, though.