Thanks, but it’s not that one. He does sing the song, but not in the way I remember it. In the one I’m thinking of, he sings ‘We’re shoving right off again’ three or four (or more) times, stretching out the ‘agiiiiiiiiin’. He might have been drunk, or struck on the head, or just crazy.
It doesn’t exactly match my recollection, but that’s been known to be faulty on occasion. But the way Daffy Duck sings the song (mocking the sailor) is what I was thinking of. So it looks like Conrad the Sailor is it.
The name of the song is “Song Of The Marines”. It’s been around since 1937. I believe the other posters are correct with the Looney Tunes episode (“Duck Amok”). Non-Daffy Duck/Conrad versions are all over youtube.