I don't drink coffee - I'm a tea drinker.
When I was a teenager working in a restaurant, customers would want iced coffee. My boss showed me how to make it. Place a plain table knife (all stainless steel) in a tall glass, fill with ice, then slowly pour hot, fresh brewed coffee into glass and let the customer add sugar if they want it. Still not sure why the knife, but my paternal grandmother also did this with a stainless steel serving spoon when making camp style coffee.