/ʒanfutʁ/
Jean stands for John or any very usual name. Foutre means uh... semen. Not a very polite word. A Jean-foutre would be a useless jerk. Totally outdated.
The insult is typically used by a well-established, slightly overweigt bourgeois who loses his temper, in a mid-Tewentieth century movie.
'There is no way you are seeing this Jean-foutre again, young lady !'