Weird gurgly noises in a bunny’s tummy is normally gas/air buildup (which you can help relieve with a tummy rub.) When a bunny drinks very fast they can take in a lot of air which can cause them gas/bloating and gurgling. The gurgling noises from the tummy can be the ones to keep an eye out for, because gas in a bunny can cause them some pain / problems. If it’s not coming from their tummy, then your bunny is just normally showing contentment. (Grinding the teeth — not crunching, but gentle grinding — as well as gurgling are happy noises.)
If you notice that your bunny’s tummy looks swollen or tight, try to massage your bunny’s tummy by first trancing them, then very gently rubbing the sides of their tummy (they don’t like the WHOLE tummy rubbed, just the sides.)
If they stop eating/drinking/pooping – they might have a blockage or be sick: http://houserabbit.usersource.com/GIStasis.htm Call your vet’s emergency number.
(My bunny ate some of a plastic bag and had a monstrous amount of gas buildup — she had to have medicine and daily tummy rubs for two weeks to help her.)