What do these dreams mean?

I had these two dream last night after I woke up at 6. The first dream I was out in the ocean with these two guys (I'm a straight boy btw) and there was a shark around us the shark came up and bit my knee off then I woke up all stressed out. Then I fell back to sleep that I was at a party or something and trees and barns kept catching on fire. I was sitting on top of a fire engine watching them put out the fire but then I get down to get on an old broken roller coaster that's in the middle of nowhere with my grandpa. I get on it all it is is the same hill up and down but when I start going up the hill the third time I fall off and catch myself and climb down. Then I see my dad and my grandpa who acted like I never fell freak out and tell me to hide because we were being attacked. I refused to hide and they stopped hiding too. Then they said the attackers were coming back and we his underneath the roller coaster and my alarm when off in my dream I woke up cause my phone went off :\. * NOT A DREAM* In real life my grandpa is alive and lives with us and just won our family $2000. What do these dreams mean?