The version I know ends "I get real crazy when I'm fucked up". To deconstruct the joke: the punchline is absurd because the monkey ordered the sour cream when

The version I know ends "I get real crazy when I'm fucked up". To deconstruct the joke: the punchline is absurd because the monkey ordered the sour cream when it was completely sober, thus setting itself up for the craziness in the first place.