I would love to have my emoticons with me - when I got freaked out I could hold up a sign with on it ! most of the time it would prob be either or or more likely

Seriously a hand signal sounds good - or just say "ive gone blank"
with T I would say "Ive lost my words" at work I say Whoa! my one brain cell jsut went to sleep - what did you say?"

I hope you fnd somthing that works for you