Does dude mean a hair on an elephants butt?

No. It is a noun. It is a slang Word for a fellow or chap or man. It is english. It originally meant a 'stupid' person from the Eastern US traveling West. They were city dwellers that didn't know the proper ways to live in the country, so 'dude' was originally used as an insult.

Today, it a casual greeting, used mostly amongst people born after 1975, or those with backgrounds in Surfing or other outdoor sports, or those in California and Hawaii.

Occasionally, elementary school children will use a common 'innocent' Word to mean something vulgar. Then they can 'swear' or 'cuss' with their friends, and manipulate their parents or teachers. Remember that Words have meanings as to how they are used. If a child wants to swear using different Words, the punishment should be the same as using regular swear Words.
no. this is an urban myth. it was first used as a term for a wealthy, well dressed man. it was a term of endearment.