Where it comes from
Samberg says 'our little guy's got burrito brain' and 'a major case of the BBs'.
How the hosts use it
Teasing a host (usually Jorma) who is rambling, confused or too deep in burritos.
Why fans love it
A fake medical condition treated with grave seriousness ('it's a real affliction and needs to be addressed').
Written by the AI from the transcripts. Every sentence was checked against them, one by one (the full episode transcript wherever a sentence names one); 5 sentences that failed the check are left out. How the check works.