"Hubert Humphrey goes politicking" joke

I can't remember where I read this several years ago but it was
alleged to have really happened.
Back when Hubert Humphrey was active in politics, he and his campaign
manager took a few days for a fishing trip in Northern Minnesota.
While they were in a small town, a bus-load of tourists pulled in.
The manager suggested that this was a good opportunity to impress a
few voters and that he should go on the bus and "pump them up" a
bit, then Humphrey could go shake everybody's hand. This sounded
good so the manager got on the bus. However instead of introducing
his candidate he pretended to be the mayor welcoming everybody to
town. Then looking towards Humphrey he said, "I guess I should
mention that we have a guy here who thinks he's Hubert Humphrey, and
he does look and talk an awful lot like Hubert Humphrey. But he's
a harmless fellow and we kind of like him, so we'd appreciate it if
you would just kind of be nice to him."
After Humphrey shook their hands he commented on how strangely they
acted.