Sister doesn't realize that she could have been hurt or worse?

My sister is 9. She called me at school today (we just got out on spring break finaly) saying she was going for a bike ride.
(elementry schools get out earlier and parents weren't home) I told her to stay at the house when i'd get home 10 minutes later we would go for a ride. When i get home she is not there her bike was gone and her helmet was lying on the ground. So i call my parents and get on my bike and ride over the neighborhood and can't find her,I like ride around for 30 minutes and i am fraking out Then i finaly see her playing near a construction site in a creek full of high water ( we sometimes do that but i have stressed over and over that she need to have someone w/her) ! I took her home but my brainless sister does not see what the "big fuc*ing deal is" (her words) I don't want to be her when dad comes home!
She scared the living shi* out of me and just doesn't seem to care.

how can i make her realize that this is a big deal

Unfortunately, many kids think they're invincible until something happens and they actually get hurt. Beyond explaining to her why what she did was wrong, I don't think you can make much impact at this point. Hopefully your parents give her a strict enough punishment that she doesn't repeat the behavior, even though she doesn't see the danger in it.

I do think, however, that you are an excellent big sister! When I was your sister's age, there is no way in h*ll that my brother would have gone to the trouble to find me and make sure I was OK! Not to mention, that he probably wouldn't have offered to ride bikes with me at all! Your sister may not appreciate it now, but one day she will realize how lucky she is to have you for an older sister.

what's your question?

Is there a question?

well i would let your dad deal with her. you are not the parent he is. and he should not be putting so much responsibility on you. your sister does not respect you therefore she should not be left with you. maybe you should talk to your dad about placing her in an after school program. if she doesnt want to to do that then maybe she will start minding you.

Tell Dad evrything. He will make her see the big deal.

stop cussing at your poor sister! she doesn't know any better!

Get some stories off the internet about people who got killed or seriously injured while riding on something without a helmet and then crashing, kids who got kidnapped while going outside alone, and kids who have drowned while swimming alone, and then show them to her. That should show her what the big deal is.