what are those extras at the bottom of some comics? ads?
Yep. This one's based on an ad from 1961 for Hitachi electric blankets: "Softness and warmth even cats recognize". I can only presume that all he changed from the original is the design of the cat.
We built a snow castle!Everyone's coming over to play too.Softness and warmth even cats recognizeHitachi electric blankets140 watt family electric blanketA reference to the 1961 ad.