Well this is a first!
According to our friends at the Mirror, Reddit users are on a mission to prove that "Summer Penis" is actual factual. The idea behind SP is that a man's... thing... grows in the summer due to the pressure of the heat.
I've never thought about it but it is possible for... things to expand and contract in weather so, why not?
PS: For some reason I thought the men of the 2018 World Cup Champions, France was an appropriate pic for this story. -Buster