The Irish Rovers - Wasn`t that a party lyrics

Question

I've been going through the mentioned song's lyrics and got stuck on a few phrases:

1. They were sittin' in my back yard, blowing on a sireen From somebody's police car. What does blowing on a sireen mean? Does it just mean to whistle or something else?
2. The little bitty track meet down on main street. What does this part mean? How I understand, bitty track is tiny road made of many parts? How can it meet something or somebody down the street though?

If needed, here is link to lyrics on genius.com: https://genius.com/The-irish-rovers-wasnt-that-a-party-lyrics.

Answer 1

Sireen == Siren
I imagine this is an invented spelling & pronunciation to give it an "Irish flavour", as the band themselves traded on their "Irishness" which frankly to anyone from this side of the 'pond' was entirely subsumed by their Canadian/American upbringing. See Wikipedia - The Irish Rovers
Old American police sirens were air-powered, driven by a rotating motor/fan assembly. By speeding up & slowing down the motor, the old-fashioned rising & falling wailing sound was achieved. - Google Images

With the second part, you're breaking the phrase at the wrong point [this is why Brits use hyphens a lot, to try avoid this;) The phrase is 'track meet' - which is an American term for a track and field sports event. [It's not one you could really guess if you're not used to it - it also means nothing to a native Brit, other than having heard it before in a US context].
In this case consider it to be a running race… the idea being to see if they could run faster than the police chasing them.