D'aww, it's retarded <3
Not really retarded, more as it got the paste hardened, so it doesn't feel the pain, so when the anon asked if it was hurt, it thought he was stupid or some other thing.
It is retarded because she's calling the Mister Stupid, considering that it's the owner, paternal figure and abuser in disguise.
Those words usually lead to pain in te majority of yukkuris, so yes, the marisa is a retard for using such words.
don't forget, Yukkuris tend to forget almost anything when given something tasty
Yukkuris tend to be pretty much retarded by nature. It might be their natural behaviour, but that doesn't really seem to make it any better.