https://www.discogs.com/release/1007491-Herman-van-Veen-Opzij-Liefdeslied
Opzij is an uptempo song that calls for taking things slower. It is one of the big hits of Herman van Veen, a dutch singer that also was popular in Germany. There is also a German version of this song, and several Dutch covers.
This song was originally part of a children’s series, produced by the Bayerisch Rundfunk called Die seltsamen Abenteuer des Herman van Veen in 1977. Two years later it was also dubbed for the Netherlands. People my age still remember it, I suppose.
I also remember this song because it was used as the signal to hurry up during a tournament of miniature games some of my friends organised. It was repeated several times during the tournament, and people knew to fear it: your game has to end now. Participants called it the Hurry up song.