Interesting bit of trivia/pedantry - it's spelled "blackguard". I had no idea until I saw it in the subtitles on something I was watching the other day.
Blaggard meaning (dated) A scoundrel; an unprincipled contemptible person; an untrustworthy person. Usually, only used to refer to a male person. noun. 24. (archaic) A man who uses foul language in front of a woman, typically a woman of high standing in society.
I like berk. Much underused. Carry On Cowboy always makes me chuckle. Judge Burke, who comes from a long line of Burkes - "all his family are Burkes, married into the Wright family and became a Wright-Burke".
Silly Sausage, Big Jessie, Big Girl's Blouse, Loony, Mincing Gret Puff are my go to. Probably break a number of politically correctisms but said with all the menace of a soft blanket.