Electric slide whistle.
When you're giving CPR and their mouth is stuck petrified in an O-shape, so when you blow it makes them whistle.
A reverse-tuba that you suck air out of instead of blowing in.
Your unanswered shouts of political helplessness reverberating into a local canyon/ravine/porta-potty.
Combination turntable and kitchen stove. One side holds a record and the other side burns you accidentally when you try to scratch on it.
The approving “Ohh!” that comes after someone says, “featuring Yo-Yo Ma.”
A drum you can kill people with.
A tambourine that you shake it and it plays “Forever in Blue Jeans” by Neil Diamond.
Guitar made of wax. (Maybe filled with colored syrup like the candy soda bottles, if can manage it.)
A quintet of harmonizing dental suction hoses.
A set of decorative vases you can dramatically/percussively smash on the floor when you're mad.
Maraca filled with priceless jewels you play for rich people.
Maraca filled with popcorn you can heat up and then crack open to have a snack.
Synthesizer that has gained consciousness but you have to coax it into playing.
World's Tiniest Violin.
World's Hungriest Viola.
World's Crunchiest Gramophone.
Theremin with flame decals along the sides so it could get you laid.
If the harmonica is the “mouth organ,” then I guess you’d call this thing the “nose organ.”
Drone with a Bluetooth speaker stapled to it that plays “Hollaback Girl” that you fly over to annoy your neighbors and then they try to shoot it out of the sky and if they can then maybe they get 20 bucks, I dunno.
Combination pitch pipe-compass that will only give you middle C when you blow into it facing true north.
Trombone that slides out forever until it produces the pitch of absolute zero.