Donald Trump wasn’t referencing a terrorist attack, and he never said it was a terrorist attack.
Don’t make jokes about how he said there was a terrorist attack, because he will catch that arrow and stab you with it after writing “Fake News” on the shaft.
What Donald Trump was referring to was a Fox News documentary describing how Sweden had increasing crime rates (from a 1997-2001 study, it’s actually low now) and about how the government is covering up violence committed by refugees (questionable).
Now, he was still dealing with what was probably “fake news”, but be careful with the jokes. This is his game that you’re playing.