Birthmark
A father and a son both have the same big birthmark on their butt. Believing that the two birthmarks are connected, the son scrubs his father's birthmark to remove it—but he just can't get rid of it.

1966

2008

1989

1967

1988

2017

2016

2017

2017

2018

1991

1997

2024

2023

2006

1976

2014
1980