Here is the full list of all 16 Pirates: Golden tits: Chapter 1 achievements.
Win an armwrestling tournament 5 times
Visit a brothel 10 times
Activate a cheat mode
Beat Saint-Isidor bandits 5 times
Listen to all of the Twig's poems
Spend 100 days sailing
Finish 10 bounty hunting commissions
Sink 10 ships
Peek at the bathroom
Leave an uninhabited
Fully upgrade your ship
Spend 20000 escudo
Have a total of 10000 Escudo on yourself
Catch 50 fish
Touch Jaina while she's asleep
Journey Begins