Say you're 17 and you get 5k cash what happens?

Youre 17 and still have a bank account with your parents signature?   Also, banks could care less how much you deposit. $5,000 is nothing to them. I have more than $5,000 deposited every month. 

At 17, you should be able to go to a bank and open your own account. Do it! 

PS: By law, the bank must contact IRS and provide accompanying documents for any deposit over $10,000.  So you may deposit up to $9,999.99 with no questions asked.

Put it in a plastic bag and hide it in your dirty laundry basket.

Or put it in some old smelly trainers

The smell will repel robbers

You hang with Mat Gatez he has a lot of 17yr old girls around him all the time .

You have to turn it into the police and if nobody claims it in 30 days, it's yours (y'lls).

Then, my drug dealer and the local hooker would be very happy. 

When I was 17 and got a similar sized inheritance from my grandmother, my dad told me if I invested it in stocks, he would match it with another 5k.   And then he taught me how to invest.   And now I'm a multi-millionaire at the age of 49.

If you get 5k in the way in which you describe, some flunkie thug is going to hunt you down.    Someone is responsible for that money and they really don't want to lose their fingers or knee caps.