[Spooky23]

Ireland has/had an interesting system where they sell bonds where the interest is paid like a sweepstakes.

It’s like buying into a raffle, except you can get your money out.

[OJFord]

Sounds like NS&I 'premium bonds' in the UK. Expected rate of return is 1.4% (I think, something like that anyway) but it's paid as prizes monthly ranging from £25 to £1M - or no prize.