Within the airline industry, as mentioned above, it is inhabited by a very conservative bunch of people. The people who recruit you won't be of your 'generation' and won't care much for earrings or other such visible piercings on their employees. The only exception to this rule is for female cabin crew members who have to strictly abide by their company rules and regs on this matter, which in most cases insist on plain studs.
No male cabin crew are allowed these items and in all my years of flying have never seen a pilot (excepting Private Pilots who rightly do as they wish) wearing such adornments.
Off duty and away from work (as long as off duty is not down route night stopping and still representing your company) I guess you can do as you please
