The best real life example for me, being a parent, is the behavior of toddlers (1 to 3 years old). If you’re a parent of a toddler, just watch how they behave and try to emulate that in your game. If you have family with toddlers, go and observe their children in action.
At any rate, a low wisdom can mean any or all of the following:
Extremely gullible to a fault (Will always get suckered into a con, will always believe what someone tells them, takes peoples’ words literally - “Wow! It’s raining cats and dogs out there!” “Really?! Oh my gosh! Kitties & puppies! Lemme see!”
Never learns from mistakes (Someone hands him a hot plate he will touch it and say “Ow!” and a moment later he may do the same thing again, “Ow!” ... repeatedly until the plate cools. Think of a toddler that keeps climbing on furniture, falling, and getting hurt. After a good cry, they’re back at it minutes later.)
Impulsive (He thinks it, he does it; he thinks it, he says it. Learn to say “Mine!” a LOT.)
Has only a rudimentary concept of his own mortality (Will take extremely dangerous risks that he doesn’t comprehend as such. Sometimes he does things most people will see as suicidal and probably will be if he doesn’t have allies around to keep him from getting himself killed.)
Overly trusting (Believes everything he’s told and only catches on after repeated lessons to teach him not to trust everyone. Even then, he forgets everything he’s learned the next time the issue comes up.)
Weak-minded (Yes, we know that his Will save is going to suck, but it goes beyond that. He is the most likely to agree with whatever someone is saying or take advice/instructions to heart whether good or bad. Don’t mix this up with Charisma. He definitely has a sense of self and a good self image, but he is just incapable of thinking much for himself)
A good example from pop culture is Rain Man or Homer Simpson or even Barney Gumble, the drunk. Another is Deedee from Dexter’s Laboratory (his annoying, impulsive sister, “What’s this do? What’s this do? What’s this do?). Kelso from That 70s Show.
Hope that helps.