Large formation check-ins (checks-in?) are no problem. When we darkened the skies of Northern Ireland in the early 70s with a five-ship formation (a Holiday Maker, perhaps), we thought to liven the day and recognise our location by going as "Spud Formation".
Yes, "Spud Formation Check-in" was replied to by "One Potato, two Potato, three Potato, four". A rather grumpy ATC voice said, "Station calling Aldergrove, say again". Sheepish Leader said, "Red Section of five helicopters to taxi."
Also remembered was the inbound call to Aldergrove, "Knuts Corner, inbound, etc". The local ATC didn't respond if this unecessarily long call was reduced to "Nuts to you."