Rancid nuts are not bad for you in the short term.
So if you eat some rancid nuts you may not even get sick especially if you only eat a little bit of the rancid nuts.
However if you do continue eating rancid nuts then eventually you may get sick overtime and you may also have issues with your digestion.
Eating rancid nuts or any other rancid food is not recommended as it can potentially make you sick if you do eat them.
If the nuts are rancid the best thing to do is throw the rancid nuts out and get some fresh nuts to eat.
The rancid nuts are also not as nutritious as fresh nuts would be.
I've eaten a whole bowl of rancid nuts before and it make my stomach hurt the next day and I also had diarrhea.
So now I never eat rancid nuts because it's not worth the risk of getting sick.
The rancid nuts are unlikely to kill you but they can give you stomach cramps and diarrhea which still is not a good thing.