We, humans, are multi-threaded by design and can do many things in parallel – with two exceptions I think. The only two blocking function we have to deal with are sneezing and farting. During these times, all current activity must be suspended for the duration. And of course it can be pretty annoying (or depending on the function, embarrassing).
So next time you check in some code, think about it – is this smelly and sneezy (yep, that’s a word, now) or have I done the right thing?