bee gees

On the cover of there hit song I got a joke there are 5 people. Who were they

Which cover? This one?

Or this.

They were (in no particular order): Barry Gibb, Robin Gibb, Maurice Gibb, Vince Melouney (guitarist) , and Colin Petersen (drummer).

The two non-Gibbs joined the band in 1967. Robin Gibb left the band in 1969.

In 1970 the brothers Gibbs re-formed the band with the more-or-less official member Geoff Bridgford (drummer). And so on...

That's why publicity photos sometimes show them as a trio, sometimes as a quartet, sometimes as a quintet.