d'yer mak'er ehrmergerd

I have no clue who that is or what that says

This is a bit of an old meme. It's called "ehrmergerd"- the idea is you make this face while saying the words. So Led Zeppelin made a song called "D'yer Mak'er" which is a pun on Jamaica. You know because it's a cod Jamaican raggae song. English people have this weird fascination with Jamaica and raggae. See also Paul McCartney "Ob-La-Di Ob-La-Da" and Elton John's "Jamaica Jerk-Off." Led Zeppelin should've been making this face when they titled the song. Haha.