Let's grow a beard is best not explained. Just think about beards and how popular they are with all kinds of extremists - and other exceptional people!
Story behind the song
This was recorded as a live Video shoot in the studio, in fact the audio is from the VHS Video tape - hence the crackles.
Watch the video version if you have not already done so.
Lyrics
when I get around to it........... something like
Let's be weird, let's grow a beard .....