Ben Blatt at Slate.com offers this fascinating article regarding the most common rhymes in the history of pop music:

http://www.slate.com/articles/arts/culturebox/2014/02/justin-bieber-and-the-beatles-they-both-liked-to-rhyme-the-same-words.html

Without giving too much away, the most common words used in songs to make a rhyme are “do/you”, which the author notes is a favorite from the Beatles to Prince to, yes, Justin Beiber.

The article goes in depth on other popular rhymes and their popularity over time, culminating in a fascinating interactive chart that allows you to see many popular artists and their most used rhymes.  If you’re curious, give the link a look.