You could try using "SpeechBubble" e.g. {speechbubble "…
You could try using "SpeechBubble" e.g. {speechbubble "Oh Yeah!"}, but the Prompt filter will remove most non-alpha-numeric symbols, so in fact in this case the Prompt will actually read {speechbubble "Oh Yeah "}. Bear in mind that very few of the Models will do any serious attempt at text at all, although you might get 'something' from the SDXL Models. This is RaehoshiIllust, The first Image is the best I got from several, the next 2 are more typical of the vague symbols that appeared, if anything did at all.
In community: the-prompt-lab