Yes, lol obviously.
Some possible cases:
1) Repeated failing exams. Different med schools have different policies as to how many times you can resit or repeat years. At some point, you could be kicked out if you don't pass the exams within the time required/within the rules.
2) Fitness to practice issue. Your conduct and behaviour as a med student is taken very seriously, you are expected to behave as a doctor and if you did something really bad, that was incompatible with practicing medicine, you could be kicked out. GMC regulations etc. I guess you'd have to do something pretty bad.
3) Personal reasons. Some people find the course isn't for them, or something happens in their life which makes them decide to leave e.g. they are a musician and get a record deal (yes, it happens!). Or someone might decide to leave medicine after completing their intercalated degree.
4) Health. If someone has/develops a health condition that makes them unable to attend enough classes, study properly (pass exams) and/OR will significantly affect their fitness to practice safely as a doctor (even if they pass the exams), they could be asked to leave (I have heard of cases where final year students with severe anorexia were not allowed to practice/graduate because they were not safe to work as doctors - obviously this doesn't apply to everyone with an eating disorder/mental health condition). This would be assessed by an occupational health physician.
Some of these overlap as certain problems are somewhat related e.g. poor health could cause repeated exam failing or low motivation to continue studies.