A story Reb mendel told A few times:

As a child I had a good friend, Leizer Mishulovin. We had a break in the afternoon, and then we would return to Yeshiva. One afternoon, I was returning to yeshiva in the afternoon, and my friend Leizer Mishulovin called to me. "Mendel", he exclaimed excitedly, "I just experienced a ness!" He explained; he came home from yeshiva, for the afternoon break, and was very hungry. He went to the ice box, to see what was there to eat, and he found some 'cutletten' (burgers). He was about to eat one, hungrily, when he remembered that he was taught that if you want something very badly, then you shouldn't do it. Since he really desired the cutllettens, he decided not the eat them. A few moments later, his mother came home. "Leizer", she called to him worriedly, "I hope you didn't eat the catletten from the ice box". An ice box was then considered a luxury, that only the relatively wealthier families possessed. Since they had one, their non-jewish neighbor (who didn't own one) asked her for permission to store some of his food there. The cutlets were his, and pure treif! This was the ness that he experienced!