In the interests of not wishing to be considered one, I looked up the definition of "Gaper" on the Internet. Believe it or not, it is somewhat confusing.
Some sites claim that the phrase originated in Vail around 1986 and refers to skiers who are so taken in by the sites that they stop to stare with their mouths open. The verb describing this action is to 'gape", which would make people who do it "gapers", and you would pronounce this with a soft "a", as in "ape". I believe this definition to be the correct one.
Most sites however, think that the term comes from the gap produced between poorly fitted goggles and helmet. This would describe a skier who isn't aware that his equipment makes him look a little silly. Some sites and even think that the gap refers to boots and pants. Either way, a person with a gap would be a "gapper" with two "p"s and would pronounce it with a hard "a" as in "bat". I believe this definition to be the incorrect one.
I find it ironic that the people who produce these lists in an attempt to make fun of others, are usually getting it wrong themselves. Sometimes you make yourself look like a fool by trying to do the same to other people.