…you can order a single chocolate milkshake from Johnny Rocket’s and not worry about fighting over it because one of you likes to suck it down while it’s super thick, and the other likes to patiently wait for it to melt a bit until it’s loose and milky.
Even more telltale is the fact that you both THOUGHT of ordering the milkshake for dessert, on your walk to dinner at a seafood restaurant, at the exact same instant.