In 'Family Matters', which nerdy neighbor is famous for "Did I do that?"

In 'Roseanne', what is the family's last name? In 'Family Ties', which actor played Alex P. Keaton? In 'Full House', which actor played Uncle Jesse? In 'The Cosby Show', what is the family's last name? In 'Everybody Loves Raymond', what is Ray's job? In 'Law & Order', what sound effect separates scenes? Which 'Law & Order' spin-off focuses on sex crimes and stars Mariska Hargitay? In 'NCIS', which actor played Leroy Jethro Gibbs?