I feel like my sister is neglecting her kids?

my sister is 24 has two kids a 8 month old and her oldest is almost 3. she use to be a pretty good mother when she just had the one but now it seems like things have really gone downhill. she lets the oldest drink soda all the time but gets irritated and questions when he's running all over the house and not listening to her. he screams more than he talks and is always hyper. she lives with her bf who is the father of the youngest and he is a jerk he is mean to her oldest and never helps her at all with them. they never put stuff up and the kids are always getting a hold of things that can be dangerous. i found a nude magazine in my 3yr old nephews room. she lets him watch gory movies cause she does not think it will affect him(house on the left)which had a scene, blood and gore. she will give them tylonel just to make them sleep. and one time when i was over she gave the 3yr old a little hard alcohol cause she wanted him to go to sleep. she is always ping the kids off when people visit or we go to family functions and will not keep her eye on the 3 yr old who will run all over the place but lets us discipline him or run after him. he does not listen because she does not carry out with punishments. the 3 yr old will pick up hard dog food out of the dog bowl and eat it and instead of telling him that's not okay she laughs about it and says the 8 month old is doing it now to and both her boys like how it tastes. there's other things but some things are dangerous and im not sure what to do. i try to give her advice and so does her friends but she does not listen to us she just laughs it off. i want to help her because im worried at times about the safety of the boys and i can honestly picture something bad happening to them.