Here are some ways it can be used:
* "Don't split hairs, just tell me what you think." This means the speaker wants a straightforward answer, not a detailed explanation.
* "They were splitting hairs over the exact wording of the contract." This suggests the debate was pointless because the details were insignificant.
* "I'm not going to split hairs with you about the price." This means the speaker is willing to negotiate but not argue over small amounts.
Essentially, it's a metaphor for being overly concerned with small, insignificant differences.