>Spoil somebody’s chance of doing something.
>Making a deed more difficult for someone
>Secret or malicious attempt to not letting someone do what they can
>Spoil someone’s chances of success
This idiom originated in UK. The pitch used in the phrase is referred to as the place where a street performer stationed themselves or the site of a market trader’s stall. Queer’ has been used as a act that means ‘to spoil’ since the early 19th century. These two put collectively give the meaning of this phrase.
Example
>He queered my pitch by asking for promotion before I did.
>He queered his friend’s pitch by proposing the girl his friend was going to propose to.
>A few Political parties try to queer on another’s pitch by booth capturing during the time of elections.