Ex: At 25C and 1atm, oxygen is a gas, not a liquid or solid. No matter how many times you test that, it will always be true; hence, it is a fact.

Of course, if you ask enough questions (How do you know it is 25C? Why are you confident that instrument is accurate? How do you establish the temperature scale in question?) the person claiming it is a fact will eventually get confused (it is was something they didn't realize they didn't know), send you off to ask someone else (if it was something they know they didn't know), or bored (if it was something they know but they are tired of answering your questions) and you will be free to think the fact wasn't really a fact after all.