Both the cats were in Pathologically Affectionate Mode, tangling themselves up in my feet and climbing into my lap while I was trying to do something with the computer. Also down at my feet is the subwoofer for the PC's sound system. The thing I was trying to do on the computer was to rip the Mortal Kombat soundtrack CD into iTunes.
When you suddenly turn on K.M.F.D.M.'s "Juke-Joint Jezebel" with the volume turned to eleven and the cats almost on top of the speaker, those critters will just flat disappear.