"Why Green Beer" joke

So what is so all darned special
About this Ol' St. Pat?
A fine old priest
went to root out the beast
And made all the Irish folk chat!
Yes, he went up against the great druids
For they spoke the God words back then.
But Pat showed the king
They knew not a thing
Of One God, of hell or heaven.
So he picked up a clover to show them,
How three God's could all be one.
But how did this make
Everyone go and take
St. Pat's Day as one of fun?
Tho the leprechauns now all wear green,
And songs to St. Pat you can hear...
It's not the shamrocks,
Or wearing green socks...
' tis cuz Pat invented green beer!