Musical Bra. Not, perhaps, two words you'd expect to see together, but somehow hypnotic now that you do. Take one bra, add to it the guts of a cheap electronic musical toy - such as the $1 toy keyboard used in the original Instructable - and then hit the streets asking strangers to palpate your tuneful chest.
Each breast gets eight different sounds, triggered by custom-made fabric buttons constructed from layers of conductive material separated by strips of foam. These are sewn and ironed (using double-sided interfacing, which glues on when heat is applied) into the bra, before a final layer of plain material is fixed onto the inside to prevent any unpleasant breast-wire interfacings.
The speaker goes up front, and a battery holder in-between the shoulder-blades. You could put together quite an orchestra using various donor toys, or perhaps even a talking version with a Speak & Spell.