CuloClean is a portable gadget that turns a plastic bottle into a bidet. I can't vouch for its efficacy but it seems like a useful alternative to wiping your bum, especially as toilet paper has become a high-value currency. Apparently CuloClean supplies are also running low but it seems like you could make one yourself that would at least approximate this $9 gadget's utility. From CuloClean:
You can easily regulate water intensity by exerting more or less pressure to the bottle. This way you will get perfect results, better than using toilet paper or wipes.
(Thanks, Bob Pescovitz!)