If your friends gave you permission it more than likely doesn't count because they do not own the house. Permission to enter is up to the owner, and if they told you in the past to not come over and you did, yes you can be in trouble. It would be misdemeanor criminal trespass if they decided to press charges.
RetiredKop is right! also,the parents may not want others there in case of emergency. in that case the parents themselves might be in trouble. they own the house ( I assume) , so are responsible for what happens in their home.