Peanuts by Charles Schulz for February 05, 1981

You can tell this is simply Linus’ way of choosing to purposely ignore Lucy.(He really did hear her the first time.) Seems he should have done to her, what Ernie had done to Bert, in that one early Sesame Street skit—removed the volume knob from a radio, and put it on Lucy’s stomach, then switched it to OFF, so as not to have to put up with Lucy’s CONSTANT yelling at him, and thus Lucy would be able to do no more, than speak, or yell, in pantomime, of course(like Bert had done, once Ernie had removed the volume knob from the radio, and put it on Bert’s stomach, and turned it to OFF, so as not to have to put up with Bert yelling at the top of his lungs—SAME DIFFERENCE.) Ha, ha. Yes, I’m just being silly.

My take is that Linus’ eating of toast really is supposed to be so loud that he really can’t hear her, especially since the last two panels seem to point to this actually occurring rather than him making it up. Perhaps inspired by a similar incidence in Schulz’ life? Or else by just noticing how noisy toast can be (when being eaten that is), thus making this situation at least somewhat plausible.