The more serious the matter, the lighter the expression
The other day, I was told something funny about British English, which is actually quite well known.
There are lots of words and phrases that are used quite often, particularly in the UK.
One of these is "a bit of nightmare", which is actually my favorite.
If you had a serious accident, you might say, "It was a bit of a nightmare" or "It was a bit rough."
If this was a serious accident, such as a major car crash in which you broke your leg, still, you can use the word, " a bit of ".
On the other hand, if you spilt some beer on somebody's shirt, which is a relatively minor incident, you might say, "It was an absolute nightmare! or It was absolutely terrible!, exaggerating the situation.
In the UK, the more serious the situation, the more understated the expression tends to be.
IIn Japan, we have similar expressions when it comes to understatement, which I find really interesting.