Thefts?

So I've met some really nice people down here at Portsmouth University.

A good friend here regularly hosts house parties as he is in private accommodation; this usually results in lots of people, lots of drink, and pleeeenty of drunken antics.

But, there is always the spoil sports. Why do people feel the need to steal at house parties?
Cigarettes, alcohol and aftershave were taken - really do not understand how people can be so mean like that.