I came across the line, “In the orphanage he shared with Puss, H.D. was the youthful butt of excruciating jokes (or eggscruciating yolks).” in Time magazine’s review of the newly released animation, “Puss in Boots” under the headline “Antonio Banderas in Puss in Boots: One Cool Cat.”(October 28).
"Humpty is Puss’ childhood frenemy: pal, rival and seemingly inept marplot to our hero’s suave efficiency in a crisis. In the orphanage he shared with Puss, H.D. was the youthful butt of excruciating jokes (or eggscruciating yolks). Ever since, he has sought revenge against the world, Puss possibly included, as he searches for the magic beans from yet another fractured fairy tale."
I don’t understand the meaning of the line “H.D. was the youthful butt of excruciating jokes (or eggscruciating yolks).” Though I think it is a pun of “excruciating jokes” and “eggscruciating yolks,” it is difficult for a non-native English speaker to grab the fun or gist of this phrasing.
What is the connection of “excruciating jokes” and “eggscruciating yolks”? I mean, what is the fun and humor of putting “ excruciating joke” and “eggscruciating yolks” in juxtaposition but for rhyming? After all, what does this line means?
Besides, I can’t find the definition of “eggscruciating” in neither Cambridge nor Merrimu-Webster Dictionary. Is it the writer’s coinage in an attempt to make a play of word?