The origin of which, for those who aren't familiar, is a game called "hot potato" where you try to pass a ball around as quickly as possible as if it was a hot potato
It is the inverse of “hot potato” routing where the network tries to get rid of a packet as soon as possible (that is, drop a hot potato). Cold potato means the network keeps the packet on-network as long as it can.
Hold onto the packet for as long as you can vs hand it off to your peer as quickly as possible.
Most networks do "hot", Google does "cold" since their network is almost always better than that of the peer.