I cannot answer definitively, but I seem to recall that what your friend says is true, though it may depend on where you’re travelling.
I believe that The Netherlands requires your passport to be good for at least 6 months past your departure date. Other countries may have different requirements so you really should look into it.
Ooooops… according to the Netherlands Embassy website your passport needs to expire no less than 3 months after your return home, not 6 months as earlier posted.
My travel agency always sends me an email telling me that my passport has to be good 6 months past my return date every time I book a trip out of the country.
This is from the US Dept of State website on travel
Some countries require that your U.S. passport be valid at least 6 months or longer beyond the dates of your trip. If your passport expires before the required validity, you will have to apply for a new one. Please check with the Embassy or nearest Consulate of the country that you plan to visit for their requirements.
Unfortunately, on that website when you ask for information on countries that start with “M” through “O” (I’m headed to New Zealand), you get sent the the list that gives “A” through “C”. I found the e-mail address for the NZ embassy, and have sent the inquiry to them.