My top 3 favorite unnecessary and incorrect plurals: 
  1. Yous (as in "Hey yous guys")
  2. Thems (as in "Thems fightin' words")
  3. Alls (as in "Alls I want to do is talk like an idiot")
On a similar note, my top 3 favorite unnecessary and incorrect animal plurals: 
  1. Deers
  2. Fishes
  3. Mooses
And on a slightly less similar note, my favorite incorrect use of a possessive pronoun:  I's as in "Come to Dave and I's house at 7:30". #language