The Law of Exclamation
First recorded in an article by Lori Robertson at FactCheck.org in 2008, this states: "The more exclamation points used in an email (or other posting), the more likely it is a complete lie. This is also true for excessive capital letters."
It is reminiscent of the claim in Terry Pratchett's Discworld novels that the more exclamation marks someone uses in writing, the more likely they are to be mentally unbalanced.
According to Pratchett, five exclamation marks is an indicator of "someone who wears their underwear on the outside".
I do use a lot of exclamation marks.... but I wear my underwear on the inside...(if I'm wearing any at all!)