No seriously, the people he's hanging with a worrysome. He wrote that after he cracked a few of those jokes one of the other guys got all serious and said
"Please can we stop with all the WW2 jokes? My grandfather died in a KZ camp".
Everyone proceeded to feel bad and got quiet, he then went on
"Yeah, he got up one morning well knowing that it would be his last day at that place. He went outside to start working. Sadly he slipped and fell off the guard tower"