Learn Bozo's magic words | Convince Spunky Goal
Proceed to Little Venice and enter the gun shop. Talk to Bozo (if he isn't here, it means that he is still in the tavern, as you haven't convinced him to visit Bambina), who, convinced by Rufus, will knock on his lover's door. Unfortunately, his magic words will be deafened by the singing gondolier. Travel to Doc's workshop and pick up a screwdriver found on the desk on your left.
Go to the tavern and set the jukebox to play the mating song of the junk crabs. Return to the area before the tavern and repeat the action with the sugarbowl on the generator. Get inside the tavern and open up the jukebox flap. Take the mating song of the junk crabs and give it to the gondolier. Click on the bumper - the gondolier will visit the doc for a new one.
Once again, convince Bozo to knock on Bambina's door. This time, the song will summon crabs which will gather in the pink pipe on the left side of the location. Turn the handle next to the pipe and travel to the marketplace. There is a pipe diverter next to the apothecary - take a look at it and connect the red pipe with the green one. Now, return to the gun shop and turn the valve. Travel to the gondolier and kick on his bumper before the boat. Gondolier will embark on a journey for a new airbag, but this time, it will be filled with crabs. Once again, convince Bozo to talk to his lover. You'll finally be able to hear his magic words.