Yep. That's ice cream. Actually it's imitation ice cream, which is important to note because it smells worse than genuine ice cream when warmed. I found this in his closet...on a school uniform...and a library book...and the carpet...about an hour after the perp committed the crime. (The fake ice cream was kind of dried out. It looks slightly frozen, but it's more just a foamy mass.) I guess #5 was too chicken to follow through with stealing the ice cream to eat it, so instead he just hid the evidence.
The good news? I didn't get overly upset in his face. In fact, I handled the whole matter rather calmly. This incident occurred last month, and I am also happy to report that the smell is finally gone--or at least it's overpowered by the smell of cat that we get whenever we have moist weather. (I didn't know until a couple years ago that cats spray their territory with their scent. Gross! My apologies to all who drop by after a rain storm. I can only imagine what it would smell like if they were indoor cats.)