The title is a reference to Dante's "Seven Deadly Vices," a Roman Catholic tradition for the seven deadliest sins.
These Seven Deadly Vices are: Pride, Envy, Anger, Laziness, Greed, Gluttony, and Lust.
The first item would be considered immoral from a Roman Catholic mindset, and also personifies greed.
The other two items can probably be classified under "Gluttony." One of them is indeed "Deadly" in that it is detrimental to your health.
The third item is a somewhat addictive habit that is frowned upon by some Christian or otherwise religious circles.
The first item has to do with gambling.
The second item will cause lung cancer.
The third item has to do with drunkenness.