Jim and Mary were both patients in a mental hospital. One day they were
walking past the hospital swimming pool, Jim suddenly jumped in the deep
end. He sunk to the bottom and stayed there. Mary promptly jumped in to
save him. She swam to the bottom and pulled Jim out.

When the medical director became aware of Mary's heroic act he decided
to discharge her from the hospital, as he now considered her obviously
mentally stable. When he went to tell her he said "Mary, I have good
news and bad news. The good news is I'm discharging you, because you
were able to jump in the pool and save the life of another patient,
which indicates that you've regained your sanity. The bad news is, Jim
the patient you saved hung himself with his bathrobe belt in the
bathroom. I'm so sorry, but he's dead!.

Mary replied "He didn't hang himself. I put him there to dry"...