First ideas were crass. As our average age is (subject to verification) 61.8 years, we've currently settled on "Fossilised Rock". Opinions are divided still, principally along the line which separates us, the 'boys', from our spouses. We think it suits us as we don't want to take ourselves too seriously.
Our wives, who know only too well how appallingly rough we sound at present, have expressed dismay at the self-deprecating tone in this name; a bit of a pleasant surprise I suppose as normal reaction to wrinkly men playing young men's games has tended to be rather more disparaging.
Ah well, it should keep us out of mischief.
For the interested (or intrigued, incredulous), we're attempting stuff up to 50 years old - Elvis, Buddy Holly, The Everly Brothers, The Shadows. Also some 'newer' stuff by Dylan, The Eagles. Next stop: some bluesey Clapton perhaps, but not until we can get through our initial repertoire (9 numbers would you believe) without too many hitches.
Don't laugh, it's rude. One day I'll maybe put an audio file on this blog - but that's not a promise...
Mapmaker