The old standby, as time-honored as milk and cookies, provided you lay the correct foundation. The veteran move is to check the forecast a day or two in advance and start hinting at an impending illness the afternoon prior. A sniffle here, a wince followed by a rubbing of the abdomen. "Ooh, I don't feel right." Then the next morning, the inevitable email: "Man, this thing hit me hard." No questions asked, and you have the added benefit of co-workers corroborating your story. "Yeah, he looked pretty bad."