I realize this is a totally random question, but every time I fly internationally I see a separate line for crew members in customs. I realize that flight crew have to go through the checkpoints, but I was just wondering if they had to have their passports stamped each time they pass through, or if maybe they had some kind of special setup?

Quite the coincidence; I was just pondering this out loud to my wife the other day as we flew back from AMS.

Great minds must think alike

In a vast majority of countries, crewmembers travel on the basis of a document called the "General Declaration" which is covered in ICAO Annex 9 Appendix 1.

The General Declaration, among other functions, serves as a de-facto collective passport for crewmembers and depending on the jurisdiction, permits the crewmember to enter and remain in the country on the basis of the submission and approval of that document for a limited period of time until their departure.

It is very rare for a crewmember to be subjected to individual immigration inspection (the USA is the most notable exception to this convention) and in most countries the crewmember's personal documents are never even glanced at by the officials.

Of course, some countries have slightly varying regulations, but for the most part the above convention holds true worldwide.

Does this apply to customs or just immigration?

Just immigration. Air crew often face strict customs inspections especially when returning home.

Depends on the country. The usual requirement is for copies of the General Declaration to be submitted to Immigration, Customs and Health authorities. Where these functions are combined or split (eg. Health/Agriculture), additional copies may be required.

From personal experience, some places (eg. France) really don't even care about the General Declaration. If you look like you're wearing a uniform, they wave you through. Others (eg. Angola) are a lot stricter and they scrutinise the lists very closely, especially the Health declarations. Most countries just do random checks for customs purposes though, similar to what they do on the passenger side.

So if i want to sneak into a country I should buy a flight crew uniform.

Depends on the country. China is stamp happy and in less than six months has almost filled up my standard passport. Egypt is the same way. Kasahkstan scans the passport with a document reader. Most countries realize that crews travel extensively and usually don't stamp crew passports unless it is requested as a souvenir.

On my flight last week from ORD->YYZ there was a pilot a few rows in front of me and before landing the FA made him fill out special paperwork. I'm sure there is more to it than just a uniform.