Casual, slang, and negative references to mental illnesses have become somewhat common in our culture. Often, people don’t intend any harm when they use them, but the fact is, they can be harmful to people with mental illnesses. Phrases that reference mental illness terms in a negative or disrespectful way are born out of the stigma attached to mental illnesses and their use makes it harder to move beyond that stigma. And, if their use makes anyone feel uncomfortable, sad, or upset, even when that is not the intention, the respectful response is to refrain from using these comments.
Crazy is one of the more common terms in today's society. Sometimes, individuals will suggest, "Oh, you can't be suffering from a mental illness - you're not crazy!" This association is incredibly hurtful.
Suicide is not a crime, therefore it cannot be committed. This associated leads to intense guilt, shame, and feelings of sinful behavior. Instead, say "died by suicide."
"That must be a challenge."
When people infer that working with, being friends with, or speaking with mentally ill individuals can be "challenging", it creates intense stigma for those who suffer. In addition, you never know who around you has a mental illness (or who is affected by one), so don't assume that if you're in a group of people, someone isn't suffering.
"It's just psychotic how these people act."
'Psychotic' and 'crazy' are examples of "ableist language", and should not be used as adjectives.