Green’s Dictionary of Slang

a general intensifier, enormous, lit. ‘a mother of a’.

1982		P. Slabolepszy Sat. Night at the Palace (1985) 13: Jeez! I mean, take last Saturday, Katz has that moersa argument with the ref – you know what Carstens tunes him?
1989		P. Slabolepszy ‘Smallholding’ Mooi Street (1994) 172: A Father is a king in his own castle, that’s what they tell you. But it’s a klomp twak. Nothing but moersa klomp twak.
1993		Sun. Times (S. Afr.) 4 Apr. 17: The notice board [...] advertises a forth-coming event, a moersa party [DSAE].
2005		A. Lovejoy Acid Alex 170: I can see he has a moerse cockstand. [Ibid.] 212: The doctor walks up and klaps a moerse fat needle into your heart.