Replying to Problems with dingus?

So, apparently people take offense to being called a dingus? I always thought of it as a silly sort of poke fun at ya type of insult, like calling someone a ding dong... But recently I've started using it and people get geniunely offended. I called my dad a dingus and he was like "hey watch it buddy" like I just called him a jerk or something. I was also talking with another friend and she was legit unhappy with me...

Is there a secret meaning I don't know about? Is it like Swahili for cock sucker or something? Or are people just dumb and have no sense of humor...