queer someone's pitch spoil someone's chances of doing something, especially secretly or maliciously. British

☞ This phrase originated as 19th-century slang; early examples of its use suggest that the pitch referred to is the spot where a street performer stationed themselves or the site of a market trader's stall.

1973Elizabeth LemarchandLet or Hindrance He's a decent lad…he would never have risked queering Wendy's pitch with Eddy.