Me and some friends had them too, we snuk inside a gym like an half hour before ppl went in for volleyball training. 1 of us went to licht switches
turned them off and me and 2 others all threw 1 smokebomb inside the hall.

once we threw them we started running like hell and the ppl from the gym started chasing us, it was great except that 1 of us got caught and had to go with the police, he got charged for vandalism.