There are two references to a song by the band Tool called 'Ticks and Leeches'. Early in the game look closely at one of the walls. You will see the words 'Ticks & Leeches' which references the song. This is not a coincidence, as later in the game, about where the Noosemen appear, written on the wall are the words 'Suck Me Dry', which is a phrase constantly repeated in the song. Also, the phrase 'I hope you choke' or 'I hope you choke on this' can be found written on a wall some time before the gun fight with the guards and the man with the gun turret. This is also part of that song.