I said that it is theoretically possible to work out the optimal neck length for coffee at a given temperature, so the warmth of the coffee is acceptable to the Giraffe. To take it further, for a specific Giraffe, whose neck length is known, you can work out the acceptable coffee temperature at the point of entry ( its mouth). And mentioned to my friend that she can ask this question to the site xkcd.com. The person who runs the site actually has a section that answers hypothetical question in a serious scientific manner.
When Randall Munroe, who runs xkcd.com and answers hypothetical questions at http://what-if.xkcd.com/, comes out with a book of such questions, with more than 50% totally new, it does need a special mention.
So, just to re-iterate, 'What if ' is a book that provides serious scientific answers to absurd hypothetical questions. the questions, to quote a few examples like 'what will happen if the sun suddenly goes off ? ' or 'how high can you throw a ball'.
If you are the curious type who wondered during college whether it makes more sense to get coffee cold because you get more coffee, work it out :) , then this is your kind of book.