So when did little yellow birds start flapping around in people's armpits?

[charlie and algernon]

Are these guys a newly discovered species or something?

[RandomThoughts]

1. No it was explained long ago.

Luke 13:

18 Then He said, “What is the kingdom of God like? And to what shall I compare it? 19 It is like a mustard seed, which a man took and put in his garden; and it grew and became a large tree, and the birds of the air nested in its branches.”

Not in the armpits, but in the branches, but you are close.

[MilesColtrane]

2. I've seen them circling people's heads after they've been bonked in the cranium.