At my former employer (small one, ~80 employees) we had a similar situation. One of engineers left the company (with good-bye lunch and all) and showed up back

At my former employer (small one, ~80 employees) we had a similar situation. One of engineers left the company (with good-bye lunch and all) and showed up back 2 weeks later. I don't know what happened (we weren't close enough for me to ask just like that), and it was a basis for jokes for couple of weeks or so. But after a month everybody almost forgot about it.