A shlub is a person who is not very good at things or who is not very important.
The word shlub can make people think of someone who is not very smart or who doesn't try very hard.
Examples:
He's such a shlub, he can't even tie his own shoes.
Don't be a shlub, try your best!
The shlub at work always messes things up.
I feel like a shlub when I forget my lunch.
The king made the shlub a knight for trying so hard.
The shlub tried to fix the car, but it didn't work.