When an
animal (humans included) is so horny and eager to mate, that they'll hump whoever comes along.
Some
people think that only females experience this state, but male animals also have a reputation for being achingly
randy.
"Great...! Just great! We forgot to neuter our
cat, and now she's in heat! I can't stand the howling!"
"While in Frankfurt (appropriately), I once asked a
German storekeeper for a 'heißer Hund'- literally 'a hot dog.' He burst out laughing, as 'heißer Hund' in
German suggests a dog in heat." -Richard Lederer