Okay - let's try this. It may not be correct - but this way it's posted and I'm SURE someone will come along and correct me.

I'll drink one, if you'll drink two,
And here's a lad that will drink with you.

CHORUS: And if you do as I have done,
You’ll be a good companion.
Companion, companion,
You’ll be a good companion!

I'll drink two, if you'll drink three,
And here's a lad that will drink with ME! CHORUS

I'll drink three, if you'll drink four
And here's a lad that will drink some more. CHORUS

I'll drink four, if you'll drink five,
And here's a lad that'll drink while he's live. CHORUS

I'll drink five, if you'll drink six,
And here's a lad that'll drink 'til he's sick (or drink like bricks [which never made any sense to me]). CHORUS

I'll drink six, if you'll drink seven,
And here's a lad that'll drink in heaven. CHORUS

I'll drink seven, if you'll drink eight,
And here's a lad that'll drink 'til it's late. CHORUS

I'll drink eight if you'll drink nine,
And here's a lad that'll drink any time. CHORUS

[Note: until this point, each verse and chorus gets faster and faster...for last verse slows down again and last line of chorus gets doubled)

I'll drink nine ... if you'll drink ten ...

And here's a lad that'll drink again ... [Spoken: again and again and again]
And if you do ... as I have done ... [You’ll be drunk!] etc.