Now here are Jean-François de Nantes lyrics with a literal translation and you can check that even if the tune is somewhat alike the one of "Boney Was a Warrior", the topic is quite different.

1. C'est Jean-François de Nantes          It's Jean-François of Nantes
Oué! oué! oué!          Yeah, yeah, yeah
Gabier de la Fringante          Topman of La Fringante [Spry, Smart]
Oh! mes boués!          Oh, my boys!
Jean-François!          Jean-François!

2. Débarque en fin d' campagne          Disembarks at the end of a campaign
Fier comm' un roi d'Espagne          Proud like a king of Spain

3. En vrac dedans sa bourse          In a jumble, in his purse
Il a vingt mois de course          Are 20 months [earning] of privateering

4. Une montre une chaîne,          A watch, a chain
Valant une baleine!          Worth a whale!

5. Branl'-bas chez son hôtesse,          Bustle at his hostess'
Bitte* et bosse et largesse          Bollard, mooring rope and largesse

6. La plus belle servante,          The prettiest servant
L'emmèn' dans sa soupente          Takes him in her attic

7. Et Jean-François qui bande,          And Jean-François gets hard
Les couilles frémissantes          His balls quivering

8. Met la fille en carène          Puts the girl in hull
Lui plant' un mât d' misaine          Sticks her a foremast

9. Il vid' une bouteille          He empties a bottle
Il reband' à merveille          Gets wonderfully hard again

10. La grand' Ursule il baise,          He fucks the big Ursule
Puis il encul' Thérèse          Then he buggers Thérèse

11. Son foutre qui déferle          His cum that unfurls/surges
Étouffe les femelles          Suffocates/smothers the women/bitches

12. Son hôtesse se fâche,          His hostess gets angry
Mais il l'envergu' en vache          But he "in-yards" her cow-like/harshly(?)

13. Montr' et chaîne s'envole,          Watch and chain disappear
Mais il prend la vérole          But he catches the pox

14. À l'hôpital de Nantes,          In Nantes' hospital
Jean-François se lamente          Jean-François laments

15. Et les draps de sa couche,          And the sheets of his bed
Déchire avec sa bouche          He tears with his mouth

16. Son vît fendu en quatre!          His dick, split in four
Pleure dans un emplâtre          Weeps in a bandage

17. On lui ouvr', on lui fouille,          They open up, they search
La plus bell' de ses couilles          His finest ball

18. Il ferait de la peine,          He would make
Mêm' à son capitaine          Even his captain feel sorry

19. Pauvr' Jean-François de Nantes!          Poor Jean-François of Nantes!
Plus jamais ne rebande          Never gets hard again


*Note that there might be a pun on verse 5, line 2, "bitte" is "bollard" but also "cock" -no, not the rooster, the other one!


Alternate verses:
7. De conserve avec elle,          In concert with her
Navigue mer belle          He sails calm sea-like

8. En vidant la bouteille,          Emptying bottles
Tout son or appareille          All his gold casts off