from a misplaced comment by @user1934428 to another question

Literally, a Penner is someone you is asleep. Whether a work itself is an insult, usually depends on the way it is used. When I'm with friends over the weekend in some summer residence, I could say in the early morning to one of them:

Wir sollten leise sein, um die Penner nicht aufzuwecken.

This is certainly no insult.

But when I say about a car driver:

Dieser Penner hat schon wieder die Ausfahrt verpasst!"

it is an insult.

from a misplaced comment by @user1934428 to another question

Literally, a Penner is someone who is asleep. Whether a word itself is an insult usually depends on the way it is used. When I'm with friends over the weekend in some summer residence, I could say in the early morning to one of them:

Wir sollten leise sein, um die Penner nicht aufzuwecken.

This is certainly no insult.

But when I say about a car driver:

Dieser Penner hat schon wieder die Ausfahrt verpasst!"

it is an insult.