Thousands of year 10 and year 12 students will mark the end of their school years in the next few weeks, celebrating becoming mature, contributing members of society by getting into all sorts of youthful mischief.

Many will get caught up in muck-up day pranks, while most are already building up to the parties of their young lives at school formals and after-formal revelry.

But police are on the front foot this year, warning school-leavers to behave, or risk facing the full brunt of the law.

Traffic police have promised to crack down on dodgy driving behaviour at school formals, warning anyone doing burnouts, driving unroadworthy cars, or driving under the influence, that they will be caught and punished.

Traffic Operations sergeant Rod Anderson said his team were not the "fun police", but wanted to ensure school-leavers celebrated safely.

"We hope everyone has a good time, but if anyone wants to drive dangerously and perform a burnout, we'll be seizing their vehicle," sergeant Anderson said.

"We've seen people dropping off people at school formals and doing a burnout as they leave, now the lack of control of the vehicle really creates a danger not only to the driver but to the pedestrians in the area," he said.

"I think it's just showing off, kids being kids in front of other kids, they're letting their hair down, they've had a big year."

Police will be at school formals and around the city monitoring bad driving behaviour, checking vehicles, and conducting alcohol and drug testing.