The saying you’re thinking of is:

“When you assume, you make an ass out of u and me.”

What they mean by it

People use this line as a humorous warning that:

  • Jumping to conclusions can make everyone look foolish.
  • Assumptions are often wrong, especially about other people’s thoughts, feelings, or intentions.
  • It is usually better to ask, clarify, or check facts than to fill in the blanks with your own story.

Why it sticks

The phrase has stayed popular in everyday conversation, TV, and forums because:

  • It’s a simple pun that’s easy to remember.
  • It calls out a common human habit—deciding we “know” what’s going on without enough information.
  • It gently shames the behavior without being too harsh, so people use it jokingly to nudge others (or themselves) to communicate instead of guess.

How to apply it

A practical way to live this out:

  1. Notice when you’re telling yourself a story about what someone “must mean.”
  2. Ask one clarifying question instead of assuming.
  3. Check if your interpretation matches their actual intention.

In other words, the modern “quick scoop” on what they say about assuming is: assumptions feel fast and easy, but pausing to ask is almost always smarter.