
That would be
the MATURE thing to do.
The Big Bang Theory Season 11, Episode 15

Yes, and I think it's pretty
MATURE of me to admit it.
The Big Bang Theory Season 11, Episode 11

Adults in a MATURE relationship.
The Big Bang Theory Season 8, Episode 6

...now you're more MATURE.
The Big Bang Theory Season 8, Episode 20

Very MATURE.
You're lucky I'm out of Silly String.
The Big Bang Theory Season 6, Episode 22