what is the hardest part about eating vegetables ? their wheelchairs .
Why would you make a joke like this?
Mentally disabled people are retarded. They don't move. I mean, what's the point of them if they can't even talk or move right?
People with mental or physical disabilities never chose to be in that condition, so we shouldn't treat them as being less than human.  Their families love them and care for them, just as you would if such a thing happened to a friend.  To make jokes about eating them just makes yourself look savage and untrustworthy, so I would advise against it.