How can it be anything else? An inexplicable circular pattern right in the middle of the living room? Nothing says aliens like geometric structures that have no readily apparent source!
The circle is darkened and the fibres of the rug are melted. Clearly a tiny UFO landed here and its thrusters burned a hole into the carpet to create this perfectly round area of cooked plastic.
There can be no other explanation. Prepare to be kidnapped, probed, memory wiped, and experimented upon. Our alien overlords have arrived. Anybody want to give me a big advance on the book deal?
Perhaps a pot of fresh, piping hot popcorn was placed onto the rug. Perhaps said pot was a wee bit too hot and the guests at a party were treated to a unanticipated smell of burning plastic. Perhaps the carpet will need to be replaced sooner rather than later, and perhaps there won't be a book deal after all.