1. catcalls, hissing [noun] [het fluitconcert, de fluitconcerten] [‘fluit-kon-sert’]

"Fluitconcert" is composed of "fluit" and "concert", which translate to "whistle" and "concerto"
respectively, hence the literal "flute concerto", see 2.

However, "fluitconcert" is more known in its other context: the disapproving whistling during soccer matches, as can be heard in this video. In English "fluitconcert" would more or less translate to catcalls or hissing.

The diminutive of "fluit" is "fluitje" which was one of our early DWOTDs…check it out!

Examples:
– "Wat een verschrikkelijke wedstrijd! Logisch, al die fluitconcerten…"
("What a terrible match! Makes sense, all that disapproving whistling…")

– "Omdat de scheidsrechter steeds voor buitenspel floot, ontstond er een fluitconcert in het stadion."
("Because the referee continuously whistled for off-side, a hissing/catcalls rose in the stadium.")

– "Tijdens de volksliederen waren er diverse fluitconcerten." – "Geen respect, die supporters…"
("During the national anthems there were numerous catcalls." – "No respect, those fans…")

Related words:
– "Applaus": applause.
– "Juichen": to cheer.
– "Oerwoudgeluiden": monkey sounds (made by so-called supporters during a soccer match). Lit.: jungle sounds.

2. flute concerto [noun] [het fluitconcert, de fluitconcerten] [‘fluit-kon-sert’] 

Examples:
– "Het Rotterdams Philharmonisch Orkest speelt nu voor u het tweede fluitconcert van Mozart."
("The Rotterdam Philharmonic Orchestra will now play for you: Mozart’s second flute concerto.")

Related words:
– "Fluit": flute.
– "Concert": concerto.
– "Dirigent": conductor.