You're missing a bit of context here -- you'll notice the plate is clean and shiny. In this scene in the episode, he used the mustard and the ketchup (which you can see in the cap) to draw a face on it. In another scene in the same episode, he attempts to do pottery on a wheel, with notably poor results.
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(R-O-L-A-I-D-S?)
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http://en.wikipedia.org/wiki/Window_of_Opportunity_%28Stargate_SG-1%29