"Head Swapping" joke

An old lady is very upset as her husband, Colin, had just passed away.
She went to the undertakers to have one last look at her dearly departed husband. The instant she saw him she starts crying.
One of the undertakers strides up to provide comfort in this somber moment.
Through her tears she explains that she is upset because her dearest Colin was wearing a black suit, and it was his dying wish to be buried in a blue suit.
The undertaker apologizes and explains that traditionally they always put the bodies in black, but he’d see what he could arrange.
The next day she returned to the undertakers to have one last moment with Colin before his funeral the following day.
When the undertaker pulls back the curtain, she manages to smile through her tears as Colin is resplendent in a smart blue suit.
She says to the undertaker, “Wonderful, wonderful, but where did you get that beautiful blue suit? ”
“Well, yesterday afternoon after you left, a man about your husband’s size was brought in & he was wearing a blue suit.
His wife explained that she was very upset as he had always wanted to be buried in a black suit, ” the undertaker replied.
The wife smiled at the man.
He continued, “After that, it was simply a matter of swapping the heads over. ”