What is the origin of the idiom "a thing or two" and when to use it?

The idiom "a thing or two" can be traced back to the English language in the early 19th century. It is believed to have originated from the expression "to know a thing or two," which means to have acquired knowledge or expertise in a particular area. This phrase is used when someone wants to convey that they have some understanding or expertise in a given matter, often implying that they are not completely ignorant or inexperienced.