Why do they call Happy Hogan happy?

Related questions

1. Who is Tony Stark's best friend?
2. Who is Thor's BFF?
3. Does Iron Man marry Pepper Potts?
4. Does Iron Man have a son?
5. Who is Iron Man's nemesis?
6. Who is the enemy of Iron Man?
7. Does Thor have a child?
8. Does happy die in Iron Man 3?
9. How does pepper die?
10. Is Age of Ultron after Iron Man 3?

Tags

1. #stark
2. #boxing
3. #rescued
4. #secretly
5. #brutal
6. #during
7. #smile
8. #millionaire
9. #nickname
10. #stock
11. #ironic
12. #harold
13. #refusal
14. #hogan
15. #happy
16. #received
17. #playboy
18. #constant
19. #collision
20. #super
21. #involved