If you think I'm going to lend you money after you gambled it all away, you must be losing your marbles
He started muttering to himself and pacing the room; I'm worried he's losing his marbles
She can't keep forgetting appointments and misplacing her keys; she's definitely losing her marbles
The constant noise from the construction next door is making me feel like I'm losing my marbles
After the shocking news, she just sat there in silence, clearly having lost her marbles
Don't tell him about the surprise party; he's too excitable and might lose his marbles
He tried to explain his theory about alien control, but most people thought he was losing his marbles
The pressure of the job got to her, and she started acting erratically, as if she were losing her marbles
If you believe that conspiracy theory, you must be losing your marbles
He claimed he saw a ghost in the attic, which led everyone to suspect he was losing his marbles
You're acting very strange today.
Am I? I think you're the one who might lose your marbles.
That's a bit harsh, don't you think?
I think he's going to lose his marbles
He is becoming quite irrational
His sanity seems to be slipping away