There’s no mechanical/grammar reason but the first one is used sarcastically. When someone thinks something is a big deal/great/awesome and you say back “well that’s certainly a thing” it’s implying that the only thing you agree on is that that thing exists, not that it’s great.
The other two are nonsense and some people just find that funny.
There’s no mechanical/grammar reason but the first one is used sarcastically. When someone thinks something is a big deal/great/awesome and you say back “well that’s certainly a thing” it’s implying that the only thing you agree on is that that thing exists, not that it’s great.
The other two are nonsense and some people just find that funny.
Thank you for the explanation!