I'm printing this one out & puting it right next to the one from July 23, 2007. The girl in the next cubicle is the worst person to have to sit next to during her lunch break...
I'm positive daggle1 is right: The "slurper" is not the beverage, but Wally's own lips, which he's extending as if they were a bionic annoy-the-coworker device built into his body. Which, in Wally's case, who knows? It might be.