Drums all the way or a harmonica or even better bag pipes.

Oh, bagpipes is hitting below the belt. Stick with bongos.

As long as he's got Scot's blood in him, go for bagpipes. (You're just honoring his culture.)

Definitely bagpipes.

Or the official Dick van Dyke one man band set up, complete with cymbals between the knees.

Well, there was the Simpsons "Sherry Boppins" episode where Groundskeeper Willie played the Dick van Dyke role, which I think involved knee cymbals and bagpipes. Even better, he did the "Maniac" number from Flashdance, and doused himself with water at the climax.

I mean, if you're looking for something in the way of overwhelming counterattacks.

It's spelled "dirrty" I think.

Drums are good, as are bagpipes and knee cymbals, but drums aren't portable and the pipes have too much of a learning curve wherein the tyke might give up too soon. I vote for standard cymbals, which are portable and have a satisfyingly deafening crash to them.

You know, brass has a special way of helping family, friends, neighbors greet the new day.

Say, trumpet maybe. Bugles are less expensive yet just as grating when played poorly.

I'll agree with Gary, adding that bugles can also be used much more effectively by a 5yr old as weapons against humans, four-legged pets, and Frenchified coffee tables.