Interestingly "lolly" is used in Australian English only to refer to sweets (in UK English) or candy (in US English). I had a look on Google and it does not seem to be very common. I think it means that someone when forced not to do something stops doing it (for example, giving up alcohol or a drug) but when given the opportunity will binge or consume excess amount of the drug. They would be a bit like a child when let in a lolly (sweet or candy) shop. I am not certain about this and hadn't heard of this "syndrome."