Am Sonntag will mein Süßer mit mir segeln gehen was a German hit written in 1929 by Robert Gilbert (words) and Anton Profes (music).
I first heard and learned this song from Cornelius Neitsch, erstwhile and short-term choir leader of the DOKU-Chor, Rönnebeck, Bremen in January 2000. This is a light-hearted song from the 1920's (not really a folk song, I suppose) about young girls dreaming and mooning about their sweethearts with whom (grammar) they spend their Sundays a-sailing.
We also sing this song with great gusto in the The Vegesack Whalermen and have really turned it into folks music, even if it is hardly appropriate to our intended repertoire.

Lyrics