Confusing 'r' sounds

In their kids song "Crazy ABCs", the Barenaked Ladies sing about words that start with confusing sounds:

A is for aisle

B is for bdellium

C is for czar

However, when the song gets to "r":

R is for R-gyle

No, it isn't

OK, you're right; I couldn't find a good "r" word

So my question is: Is there an "r" word that would fit into this song? If not, is there anything special about "r" that explains why not?

Rzedowski's pine, if you base your pronunciation on the Polish one, would be "zhe-DAWF-skee's pine". However, I would imagine a lot of people don't pronounce it based on the Polish pronunciation, since few English speakers are familar with Polish. So who knows, some people probably use /r/ here ("redouski").