I would tell a joke about chemistry but I'm afraid I won't get a reaction

Two men were going around the park.
One of them dug holes into the ground, then the other would fill them in, they did this for hours, went to a break for lunch, then, as they were about to get back at it, a boy walked up to them and asked why they were doing this.

One of them told the boy "We're planting trees."
"But you don't actually plant trees in the holes" the boy said.
"Oh, that's true! I dig holes, Steve plants a tree, and Bill fills them in." said one of them.
The other then replied "Yeah, but Steve called in sick today."

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3 man are standing in a bar and are drinking beer. The more they drink the stronger their stories.
"1 day i walked into the forest and saw a bear right in front of me! I took my gun, aimed, shot and thank god he died."

Pffff that's nothing laughs man number 2. "I once walked into that same forest and saw two bears. And i only had 1 bullet. I aimed, shot and i killed both of them."

Its quit for a while and man number 3 starts talking. "That's nothing. One day i walked into that forest and saw 1 bear. And i also had only 1 bullet left. I aimed, shot and missed. So i run away but in front of me is a second bear. I'm so pumped with adrenaline i grab both of them at their heads and smack them against each other. They both drop dead.

The other two man look at him and say. How is that possible you have only one arm? "A" the 3rd man says" trust me, at that moment you don't think about those little things."