If somebody asked you something and you started talking and fumbled around for a but then simply stop talking all together I can't imagine how awkward that would be. I would rather just keep fighting through the block, even though I might sound legitimately retarded it sounds a little but better than just randomly stop talking all together. Thes dam blocks are why I have so much a anxiety because everytime I'm social I have to be ready to probably be abused if I get blocked or stutter :/