Perhaps they got together and were reminiscing about the good old days of the Ayatollah Khomeini. From [1] AP, with thanks to Twostellas:

TEHRAN, Iran - About 100 demonstrators threw stones and firebombs at the British Embassy in Tehran on Friday, damaging the building but not harming anyone as they accused Britain and the United States of being accomplices in Israel's fight against Hezbollah.

Demonstrators also smashed some of the building's windows as they called for its closure and the expulsion of the British ambassador.