Irony means an expression of someones using language which normally signifies something completely opposite or empathetic effect. Dramatic irony is used in speeches of a situation of a drama, kinda like acted out. Verbal irony is something a person says or writes one thing that is meant another thing or to use the words to convey a meaning opposite of a literal meaning.

" I find it very funny/ironic when people will go to McDonald's and order a giant Big Mac, extra large order of fries, and a Diet Coke."

As i think if i had to choose dramatic or verbal of this scenario, i would probably choose dramatic irony because its kinda acted of and type of a show. The irony of this is the Diet Coke because he he got so much fatty food and getting a diet coke over it, is hilarious and showing that things on his aren't all full of fats. Most times irony is made/said not to insult someone directly or harshly.