1. A large firework, about the same diameter as a king-size cigarrette and two-thirds the length. Used in Austarlia and New Zealand for the same purposes as a Cherry Bomb, e.g., toilet cistern mayhem.
2. A form of mutual masturbation; The male lies on his back and performs as for a normal "handjob', while his female partner straddles his thighs and moves herself into such a position so as to stimulate her clitoris upon his moving hand. ( Caution: While a safer sex practice care must be taken to assure no fluid from the male lands on the vagina.).
1."Someone stuffed a double happy in MUzza's exaust pipe - Tore a hole in the muffler!"
2."We ran out of condoms, so we had a double happy instead."