To build a Polish Beach House, you'll need 2 giant umbrellas with long shafts, and a few beers (does not have to be Polish Beer).
You set-up the two umbrellas by planting them next to each other when the water gets to be a couple of feet deep. then, swim under your ghetto makeshift island shack with a six-pack of beer, and start chugging.
There. If people at the beach curiously point at you and are, like, "WTF??" Then, and only then, you've got yourself a genuine Polish Beach House. Make sure to snap a photo to send to Polish Beach House Magazine. If you're lucky, you'll make next week's cover.
If you add 2 more umbrellas, it becomes a Polish Beach Duplex. More than 4 total umbrellas makes it a Polish Beach Mansion.
LESTER: I've just chugged 6 beers and can't hold it in any longer and there's not a port-a-potty in sight!! What am I gonna do, Leebo?!
LEEBO: Relax, Lester. We'll set up a Polish Beach House down yonder and you'll be good to go