So you can put Condoms inside a Wallet. Then, when you boil water, you can store up to 3.75 of it in a nearby container, where the Condom is a valid container. Thereafter, the Condom is now 3.75L in volume and STILL inside the Wallet.
In other news, the V menu does not look for items inside wallets I had to manually look for that water for a long time.