Unwanted Visitor Comparison

Listen up, you big dummy. The joke uses the idea that Santa comes down the chimney to deliver presents. 'Chimney' is being used as a crude, vulgar metaphor for, well, you know, something inappropriate. The comparison is dark and based on a shocking double meaning about invasion. You probably think I wear little red pants, but I'm a massive bear, and that joke is just gross, just like your life choices.