My gf found this in a take a penny/leave a penny when we were getting food the other night. Since the weight is so off would this be the only answer or is there something else going on?
The weight is perfectly normal for coppers cents, which weigh 3.11 grams. You may have gotten the weight confused with newer zinc cents (made after 1982) which have a weight of 2.5 grams. The coins looks like environmental damage to me, probably spent some time in a moist/humid environment.
Looks like staining. Impropper mix coins appear as streaks not "blob puddles" due to rolling the thick stock down to thinner planchet thickness Think of say pie dough. If you take the blob of dough and lightly mix in a different color dough then roll it out to pie crust thickness you get a streak pattern of the 2 different colors, not blobs.
This is not entirely true. Alloy mix USUALLY appears as streaks. IMO, based on what appears to be a tiny bit of lamination on the coat and head, this IS an improperly mixed alloy coin and VERY UNUSUAL. I want it.
And this refutes my opinion backed up with good reasons. Note how the entire coin is a normal color and the dark color "lays" on the surface - sort of in a "flow" pattern. The OP is the only one who can decide which opinion is correct. If there is no peeling at all, Markus is correct.