Hosteling in Amsterdam

Amsterdam as for it size and huge amount of tourists doesn't have to many sleeping places in hostels. They do have a lot of very cheap hotels but thats not same climate like in a good backpacker hostel. Still amount of beds is not so big.
One night when I was hanging out with friends in "Lost in Amsterdam" pub a group of six california backpackers approached us and asked if we stay at our own places. It was like 1 am and they just have been said in Flying pig downtown that there is no place for them, like around 6 places they have been before. In the end we let them stay for two nights of good parties but it felt like a real hostel in the apartment. Its already like a hostel because its maximum for 4 people and we are here 7 so with california tourist it was 13. Squeezed dorm :D everybody sleeping everywhere