This is a groaner. 
Two robins were sitting in a tree. “I’m really hungry,” said the first one.
“Me, too,” said the second. “Let’s fly down and find some lunch.”
They flew down to the ground and found a nice plat of newly plowed ground that was just full of worms. They ate and ate and ate 'til they could eat no more.
“I’m so full I don’t think I can fly back up into the tree,” said the first one.
“Me either. Let’s just lay back here and bask in the warm sun,” said the second.
"O.K.,"said the first.
So they plopped down, basking in the sun. No sooner than they had fallen asleep, when a big fat tom cat snuck up and gobbled them up.
As the cat sat washing his face after his meal, he thought…
Ready?..
You’re gonna like this one…
“I just love baskin’ robins.”