Jokes from Sidney Morgenbesser

I'm enjoying reading David Edmonds's Parfit: A Philosopher and His Mission to Save Morality. Recounting Parfit's time in New York with a Harkness Fellowship, the author squeezes in some jokes from the philosopher Sidney Morgenbesser, new to me, who was teaching at Columbia. The jokes:

• On pragmatism: "It's all very well in theory, but it doesn't work in practice."
• J.L. Austin is saying that while there are double negatives to express a positive -- "she is not uninteresting" -- there are no double positives to express a negative. Morgenbesser interrupts: "Yeah, yeah".
• Eating dinner at a restaurant, the waitress says there are two choices for pie: apple or blueberry. Morgenbesser says he'll have the apple. The waitress comes back a minute later to say there's actually a third choice, cherry. Morgenbesser: "In that case, I'll have the blueberry pie."