A "red shirt" sympathiser uses a traffic cone as a megaphone. He is telling the security troops to come over and join them for sticky rice and grilled chicken.
<a href="//commons.wikimedia.org/wiki/User:Takeaway" title="User:Takeaway">Takeaway</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>