I'll go them one better.

Boston City Councilor Jerry P. McDermott crusades to take down the city's landmark Citgo sign.

I think it might be more effective to leave the sign in place and hang a larger sign just above it that says "Don't Buy".

Or, aim higher. Give Citgo the Orinoco River Treatment. Nationalize all the company's United States gas stations and other assets and divide them among U.S. companies.