The EUROCONTROL Agency has been notified on numerous occasions about the misuse of the international aeronautical emergency frequency, 121.5MHz, most recently involving inappropriate ‘chat’ related to the ongoing EURO 2012 football championship.
ICAO Provisions

ICAO Annex 10, Volume V, § 4.1.3.1.1 states that frequency 121.5 MHz "shall be used only for genuine emergency purposes" broadly covering the following activities:

The handling of an emergency situations;
air-ground communication with aircraft with airborne equipment failure;
search and rescue operations and the operation of emergency locator transmitters (ELTs); and
air policing/interception action.

Note: Some states have filed differences to ICAO SARPs related to the use of 121.5 MHz - for instance, in the UK it can also be used for practice PAN calls to ensure pilot familiarity with the process. Such differences are detailed in national AIPs.

Analysis

Inappropriate ‘chat’ on 121.5 MHz could interfere with its legitimate use and should be avoided in order to maintain the integrity of the frequency for the purposes for which it is intended.

Your Attention is Required

Aircraft operators are invited to remind their flight crews about the correct use of the international aeronautical emergency frequency, 121.5MHz, according to ICAO/national requirements and company policy.
Air Navigation Service Providers and State Aviation Authorities are invited to note the subject and share their experience with similar cases.

Further Reading

SKYbrary - Request for Support Message: Guarding 121.5 MHz - 12 March 2007.
ICAO Annex 10, Volume V.

For more information contact, EUROCONTROL Safety Alerts Coordinator, Richard Lawrence