A speech balloon on the left, a thought balloon on the right. These two, and a scream balloon, are illustrated here, along with a link to a great “Evolution of Speechballoons” site, where it’s noted that
During the 18th century, British caricaturists changed the shape of speechballoons from gothic speech-bands or flags into fluffy balloons, our modern speechballoons.
Then there’s “Who are those guys?” — a quotation from Butch Cassidy and the Sundance Kid (1969), where Butch asks this question at least four times. Here are two:
Butch Cassidy: Ah, you’re wasting your time. They can’t track us over rocks.
Sundance Kid: Tell them that.
Butch Cassidy: [after looking for himself] They’re beginning to get on my nerves. Who are those guys?
[about the trackers following them] Butch Cassidy: I couldn’t do that. Could you do that? Why can they do it? Who are those guys?
Butch’s question has been alluded to many times, for instance in the 1977 album Who Are Those Guys? by the country rock band New Riders of the Purple Sage and in the name of the “neo-classic rock band” Who Are Those Guys.