An affliction of hand cramps resulting from spending long periods of time on all fours as the recipient of anal sex (or vaginal sexdoggie style). Sometimes it involves splayed or swollen fingers that resemble a catcher's mitt. The term derives partly from catcher, meaning a bottom or recipient of anal sex.
A: How was your date last night?
B: Pretty good. We went all the way. But I was on all fours for so long and never really found a comfortable position for my hands, so I'm gonna have catcher's mitt all day today. Ouch. Probably won't be able to finish stitching that sampler till tomorrow. Oh, and my ass hurts too.