(Strip Number 4113, Original Publication Date, 25 December 1981)
Panel 1: As we go from left to right, we see the following:
1) Mike and Lizzie grinning with delight; that's because he has a trumpet and she's got a pair of cymbals.
2) Will and Carrie sitting on the couch grinning because they don't have to deal with the results of their generosity.
3) John and Elly with their faces frozen in the Bug-Eyed Glare of Existential Horror™.
Will punctuates this tableau by reassuring Elly that Carrie told them that the instruments were only to be played outside.
Summary: Lynn just does not want to give up on her favorite obsessions; even on Christmas, we have to divide by zero and deal with the awful equation "Yuletide Bliss = Poor, Put-Upon Elly." Also, Will and Carrie really don't much care for John or Elly; you'd either have to have a nasty sense of humor or straight-up despise your son and daughter-in-law to give their kids stuff guaranteed to drive them bonko.
In any event, Merry Christmas (or whatever else you observe) from me to you.