I suffer from this one too - I'd concur you really need to see a medic but if you suffer from IBS, this is actually a very common symptom. Your gut is lined with mucus and if something iritates it, you can end up with too much of the stuff. If you then end up a bit too much iritation to your anus, the mucus seem to be able to leak out. (Also it seems it happens to folks with IBS a lot if they pass wind). Obviously if it's not clear mucus - or if there is blood your are leakin - get to the medic asap and don't hang on.