Overheard in a viva voce where the questioner was a doctor and the other person was... not a doctor.

Antibody: One who hates his body.

Artery: Study of Fine Paintings.

Bacteria: The back door of a cafeteria.

Coma: Punctuation Mark.

Genes: Blue Denim

Ultrasound: Radical Sound

Cardiology: Advanced Study of Playing Cards.