...You feel more normal wearing your sleepwear out in public.
...Most of your dreams involve Sims.
...You've been told by a random Sim veteran (that's someone who played ALL the Sims Series), you look like a pre-made townie. (I got told I look like Kaylynn Langarak by a random customer at Sears while I was off the clock, and another time my sister's friend said I look like Bella Goth)
...You google the names of the foods on Sims 3 (Ambrosia, Goopy Carbonara, Lobster Thermometer, Dim Sum)
...You suddenly crave (and not while pregnant) Spaghetti after playing a pregnant Sim
...Your pet starts to behave like an insane Sim, you think "My Sim just did that"
...You're waiting for Charlie Sheen to have a self argument.