Oh he used to hang around my place too. The first time he did it he nick nacked on my arse!!!
It now occurs to me to wonder what his initial nick nack is in the USA - surely he doesn’t do that to homeless persons?
Heard at a carnival once:
From what I gather, it sounds like he is just drumming on stuff, body parts, footwear, etc. A paddywhack (roughly per Squink’s fiesty link) seems to refer to hitting something and the only thing I could come up with for Nick Nack was a Scottish rhyme, kind of like Eeny Meany Miney Moe:
Here is my source. Apairently Nieve is Scottish dialect for “Fist”. So, in conclusion, some old guy is walking around, tapping out some unheard beat on everything he can find. I can see how he could be annoying.
It’s either that or nick nack refers to the sound scissors make and the whole thing is about the torturious dissection of some Irish guy, with the Scotts one never can tell 
…Whose bones then get fed to a dog…
I thought knick knack paddy whack was describing the game knucklebones.
Don’t ask me what knucklebones is, haven’t a clue!
And how does one knick knack on a gate? Sounds painful to me.
I sing that one, too. And “The Ladies of the Harem of the Court of King Caractacus”.
I thought you were asking about that annoying old bald dancing guy who shills for Six Flags.
Hey! Maybe they’re the same guy! Maybe all that frenzied dancing is him playing “Knick Knack Paddywhack” and playing “One”, “two”, and all the other numbers.
So a frog walks into a branch bank, hops up to a loan arranger named Patricia Wack, and says, “I’d like to take out a loan.”
The banker, nonplussed at being approached by a frog, says, “Well, we’ll have to have some collateral.”
The frog pulls out a Precious Moments figurine and says, “Won’t this do?”
Ms. Wack says it isn’t good enough as collateral to guarantee the loan.
The frog becomes irate, asks to see the bank manager. Ms. Wack the loan officer calls him, and he comes out.
“What’s the problem here?”
“Well, sir, this frog wanted to get a loan, and when I asked for collateral, all he had to offer was this, whatever it is” (holding up the figurine).
The manager says, “Why, it’s a knick-knack, Patty Wack. Give the frog a loan!”
That joke has been running through my head since I first read the OP. I had been praying it wouldn’t escape and inflict itself upon the innocent. 
In 1961. For twenty minutes, right?
Actually, it’s a little known fact - his name is “Fess Oldman.”
You have to add that the frog introduces himself as “Kermit Jagger. Maybe you’ve heard of my dad?”
That way, the punch line can end with “…give the frog a loan. His old man’s a Rolling Stone!”
And the telling should take one whole pint of beer to finish, so that you can say, “So the bank manager looks at Patricia Black, and says to her…”
then turn and order your beer.
In USA, he played knick-knack on my thumb!
In Soviet Union, thumb played knick-knack on him!
I always thought it was Gary.
In Marianna’s trench, probably?
Is this old man tattered and torn, by any chance? Because if so I think the world in general ought to know that there’s a shotgun wedding in the offing, just as soon as the parson gets through shaving, which he generally does round about cockcrow. Think he can get away with harassing the maid who does my milking, does he? (Memo to self: next time you build a malthouse, be sure it’s ratproof. Having a cat kill the vermin is small comfort after the malt’s been eaten. Also, keep the damn animals apart. All this chasing and tossing and so on kicks up a fearful racket.)
I’ve always wonderered, how does the man roll home? Does he
(a) somersault down the hill
(b) curl-up in a large truck tire and that rolls down?
(c) Sit in a wagon that rolls down?
Any insight you could offer would be appreciated.
Spectre of Pithecanthropus (Mrs).
I always thought that he just stretched out on the ground and rolled sans equipment. not somersaulting, just kinda bouncing down.
But I also spent a good amount of time last night pondering whether or not “scratch” could be considered the opposite of “itch.”
So having a (noun)“scratch” in the middle of your back is the opposite of having an (noun)“itch” in the middle of your back? Interesting considering how many people use “scratch” and “itch” as verbs to mean the same thing.
The mind boggles. What do you do to an itch? You scratch it. A scratch is an anti-itch. There was a great deal more, but I resolutely forgot it all when I realized that I had spent far too much time on the subject and moved on to the difference between a hootenanny and a hoedown.