What shall I do I crashed my dads car?

Today I crashed my dads car, he was out and I thought it would be a good idea to drive it around and I smashed into another car when driving down a road, I'm 15 and the car is fine, you would barely be able to tell it's been touched but I don't want to be found out/arrested anything Only nice answers and help ful answers what do I do, my dad is still not back yet but I'm scared he will realise.