This is probably the second most commonly used logical fallacy, sometimes used maliciously and intentionally and other times used accidentally. Here’s what this one looks like:
Person A: I think prison sentences for non-violent drug crimes should be reduced.
Person B: So you want to empty the prisons and have the streets overrun with criminals?!
All executions of the Straw Man fallacy look something like this. In short, it’s when your interlocutor restates an exaggerated and inaccurate version of your argument and then proceeds to demolish their version of your argument. This is an example of one I suffered through in a college biology course from one of the other students. “Evolutionary theory says that I should be able to grow a third arm out of my chest. I obviously can’t do that. Therefore evolutionary theory is wrong.” This is a straw man because evolutionary theory does not say that and defeating that mischaracterization is not the same thing as defeating evolutionary theory.
The Straw Man can be employed deliberately, like when some young earth creationists “explain” evolution, or accidentally, like if you don’t understand someone else’s argument and you mischaracterize it by mistake. It’s easy enough to refute when someone does this to you. My favorite (I think I first heard this in a Sam Harris debate) is this: “Feel free to disagree with me, but please disagree with what I’m actually saying.” In an honest discussion, simply pointing out that you’re opponent misrepresented your argument is sufficient to refute the Straw Man.
What is harder, and requires more discipline than catching someone else using the Straw Man, is making sure you’re not doing it yourself. And what is even more important than that is finding the truth.