Find this in Ruleset/Piratez.rul within the Parrot mod
items:
- type: AUX_CARRRAMBA
size: 0.1
weight: 0
bigSprite: 1350
bulletSprite: 27
hitAnimation: 240
fireSound: [480, 481, 482, 483, 484, 485]
hitSound: 999
invWidth: 2
invHeight: 3
and change "hitSound: 999" to "hitSound: -1"