Running out of gas

An overexcited Dominic was telling an imaginary story.  Speaking rapidly, he would collapse now and then, giggling at (one surmises) funny turns in the story.  Unfortunately no one could follow what he was saying, and the story is progressing to...nowhere:

Pia: (leaning close to Daddy's ear) Look Daddy, Dominic is being silly.

Daddy: Should we bring him to a doctor?

Pia: Yes

Daddy: Yeah, I think he's gone crazy

Pia: I think he's running out of gas

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