Wine being the obvious one. Two is the optimum glasses of wine - one’s never enough, three leads to four or five. One other person is the optimum number to drink with, and 250ml is the optimum quantity per glass, so all bottles should be 1L as standard so you can buy one for a week night and two if you’re off work the next day.
Pots of tea in cafes, irrespective of size, always seem to produce 2.5 cups. Bit of a swindle. Should get four out of them so me and my georgeous funny girlfriend (having a great time, just out of shot) can both have a topup.
Stuffed pasta. Ridiculous to consider sharing between 2 but a bit more than a portion for one so you end up just polishing it off but feeling a bit over full. 200g please
A good little system is to buy beans and sausage instead - woof down the sausages cold, save the beans for beans on toast. Just the right about of beans.
I think most people shop by pack price rather than unit price. I buy them, because my brain tells me that paying 5p a bag now is a better option than spending 2p a bag but parting with an additional three pouds.
It’s foolproof. And you still get eight sausages, although they’re a bit smaller than they were. They’re 42p in ASDAS, beans are 25p - you do the maths.
I am really grumpy with how little supermarkets offer loose veg TBH. That bag of potatoes is probably fine for a family of 5 but if it’s all there is that’s frustrating for the rest of us.