Store owner

In a small town, a man just opened a small store selling trumpets and guns.

One day his neighbour pays him a visit and says "So how is your strange business going?"

"What do you mean 'strange'?"

"Because you sell only trumpets and guns!"

"So?"

"Well, let me put it this way, what do you sell the most, trumpets or guns?"

"It evens itself out. Each time a customer buys a trumpet,

Spoiler:

one of his neighbours buys a gun".