Are there any girders in the picture then? Or none, or impossible to tell? I can’t see any, by that definition.

2 units (in this case houses) down and 2 across (a perhaps intentional misinterpretation of the original slightly ambiguous statement). Reasonable to assume down and across are perpendicular directions. Let’s pretend space-time is Euclidean. How far away is the listener from the sneeze? Pythagoras, our faithful companion, guides our understanding…√(2²+2²)=√8=2√2

Is that a thing? Blowing up fully-fuelled airplanes just for fun?

In terms of blood-borne viruses (like HIV and hepatitis), breast milk is considered in the same risk category as semen or vaginal secretions, only blood is higher. Whereas piss and shit are only considered a risk if they contain blood. Obviously there’s other reasons why you don’t want shit in your food, but it probably won’t give you anything really nasty and long-lasting. Piss it’s pretty much totally safe, but I reckon you could still get in trouble for secretly feeding it to someone.

Does this also work the other way round, i.e. do all multiples of three have digits that sum to a multiple of 3? All the ones I’ve checked so far do, but is it proven?