The two rock legends came up with the bizarre portable pooch product whilst they were both recently on vacation in the Turks and Caicos Islands where they would hang out most days after lunch.
Speaking on the WTF podcast, McCartney said: ''[We were] designing portable dog kennels that were inflatable. It was a pretty good idea, we thought ... We got round to if you had one you could custom-make them for Dalmatians to be polka dot. It was a good idea, I thought.''
Host Marc Maron the cheekily asked if cannabis was involved in the creative process, to which the musician replied: ''In the kennels? In the creative process, it was required.''
Although it was often claimed that the two acts were rivals, the 'Can't Buy Me Love' hitmaker insists they got on great and respected each other's work.
He said: ''The legend grew that there was a rivalry and everything, but it was the opposite. If we had an album coming out on August 28, we'd ring them and say, 'Have you got anything coming out?' and they'd say, 'Yeah, we've got something coming out August 17,' so we'd put ours back a bit. It was a nice scene.''
The Rolling Stones - comprised of Keith, Sir Mick Jagger, Charlie Watts and Ronnie Wood - recently completed their mammoth 'No Filter Tour' which saw them sell-out stadiums all over Europe.
Asked if watching the Stones now made him wish The Beatles could still tour, McCartney replied: ''Yeah, but unfortunately two of mine are dead. You're kidding me? It would be fantastic if we still had the Beatles together to tour.''
McCartney released his new album 'Egypt Station' on Friday (07.09.18) and to celebrate the arrival of his 17th solo studio LP he is performing a concert live on on his YouTube.
The set will be comprised of his fresh material, including single 'Come On to Me', and hits from his time with The Beatles, Wings and early solo career.
The live stream begins at 8:00PM (ET) / 1:00AM (BST) on Friday night.