Verified answer

German: Lederhosen

France: a Beret and white/blue striped jumper. Maybe a moustache as well.

USA: one of those hats with drinks attached to it and maybe a basketball vest or American football top.

For Germany: search for "lederhosen"

For France: a horizontally striped black and white shirt, a beret, and a neck scarf (can also search "French costume"

For USA: a little trickier, but some ideas would be colonial dress, something from Tom Sawyer, or the Statue of Liberty.