On the Internet, what is a dead giveaway that someone is actually a kid?

https://lemmy.ml/post/17542340

On the Internet, what is a dead giveaway that someone is actually a kid? - Lemmy

Poor grammar/orthography
What do birds have to do with anything?
Dunno, better call in an etymologist to study what bugs the birds are eating.
“Ahh no see, you wanted entomology man, which coincidentally means study of bugs”
What about the study of Ents?