Two Japanese Sewer Workers

Two Japanese sewer workers started at the same time every day, shared the same locker room, worked in the same sewer, ended at the same time and never once spoke a word to each other. Fifty years later, they both retire on the same day and as a cost-cutting measure the company has a single retirement party for both of them.

At the party, they're chatting away to each other, laughing at the other's jokes and having a great time. A confused colleague approaches and says "I though you guys hated each other, fifty years and I've never seen either of you speak a single world to the other!" to which they reply:

Until now, we've been but two Nips passing in the shite.