"Yesterday was the longest day of the year, unless you count the time I interviewed Lance Armstrong," the former Tonight Show host tweeted yesterday.
The cycling legend was quick with a reply: "@ConanOBrien all you wanted to talk about was riding bikes and shaving your legs. It was, uh, slightly freaky."
The funnyman continued the back-and-forth: "@lancearmstrong - I was drunk. And I wanted some tips for smoother legs. Is that so wrong?"
What do you think of their ultra-gentle Twitter war?