What the hell is a phrase you may use when you decide that you may as well do something or go along with something, especially if you aren't excited and aren't even 100 percent sure you want to.(idiom)
An example of when you might say "what the hell" is when your wife asks if you will please go to her second cousins wedding. You might not want to, but you could say "what the hell, I'll go along."
What the hell is defined as something that you ask when you are not happy with something and you want to know what is going on and why that situation is occurring.(idiom)
When you get home and find your house a complete mess when you left it pristine in the morning before leaving, that is an example of when you could say "what the hell?"