If someone believes that Islam is a cult and not a real religion and if someone believes that Mohammad(SAW) was not a prophet of Allah , would you leave that person alone ?
Respect of a belief and religion is not demanded it is earned.
Instead of getting mad at what these people are doing or trying to do , deal with them. Do not just react , act , act in a civilized peaceful manner . They more you react the more these kind of people will try to have fun at the expense of those who react to these kind of stupid actions of these idiots.
Who is stopping you to start a fb page on showing your love to Mohammad(SAW) ? Be creative , start something which will inspire others to respect Mohamamd(SAW).