It's a typical expression used in Veneto that means "Son of Mary (jesus) is a fuckin asshole". You use it when you're angry, but not so much to say "Porca madonna".
E' finito il vino, Gesu bastardo!
The wine is finished, Gesu bastardo!

Gesu bastardo, mi è scappata la capra!
Gesu bastardo, my goat run away!
by El chiavador December 3, 2018
Get the Gesu bastardo mug.