I have two friends that live home with their parents, and both are 32.
To be fair, one of them could live on his own and works regular hours at decent enough jobs, saves his money, doesn't buy a lot of stupid shit, and is even improving himself to get better jobs, but his parents keep guilt tripping him about what they'd do without him because both are near crippled, and he has close relationships with both of them. Tight knit family, like best friends.
But the other friend doesn't have such an excuse, with his dreams of making it big with an MBA crushed and choosing not to work anything beneath him (So basically anything beneath a fortune 500 company).
So how does he spend all his time? Downloading and burning porn, and seeing doctors because he's convinced he picked up an incurable disease that'll kill him in a year. Now he's lying to his folks about getting interviews and needing money for work computers and such, and it's a complete lie for the money..
That's the potential suicidal friend I mentioned, btw. He's sure he'll be unable to care for himself due to this percieved illness, and that they'll either lock him up in a nuthouse for this, or for his refusal to work and inability to care for himself. Claims he'd rather be dead first.