Not much time to post today, I've been having too much fun playing with the Merriam-Webster online top ten lists.
Some of my favourites include:
Words For Things You Didn't Know Have Names (What's a PHILTRUM?)
Top 10 Words with Bizarre Meanings (SPANGHEW?)
Strange Words for Body Functions (MICTURATE?)
The user-submittted lists are also mostly hilarious (SLACKTIVISM - "(noun) : activism (such as signing an online petition) that requires very little commitment or action").
Of course none of these begin with R, but I was pleased to find two entries in the 'Top 10 Charming Words for Nasty People' list that do.