50 year old joke from my country

Hi everyone this is the oldest joke i know even today everyone laughs at it even though is 50 years old.

A war started and Ion was drafted, after 2 years he returns home to his wife, when he arives his wife has a newborn baby.

He starts screaming and cursing her for infidelity, she convinces him that he's the father, when he was away she realy missed him so she rubed a picture of him and thats why she got pregnent.

Ion belives here and apologise then he goes to sleep, when he lays in his bed he notices the picture of him then enraged he starts beating his wife, the picture was only his upper half.