English Expressions Usage

[Salvo]

Once again while I was watching a movie in English I heard a couple of expressions which I didn't understand. One of them was

I swallowed a bug

Here is the contest I heard it in:

Two guys were talking to each other at the pub, one of them was swearing when a girl come along to talk to the other guy.
So when the guy who was swearing realized she heard him, he said: I swallowed a bug... and took off.

I'm pretty sure it is something to do with the fact that it was swearing.

Regards
Salvo

[Conchita]

I couldn't find that expression other than in its literal meaning:

[Mister Micawber]

.
It's not an idiom, Salvo -- he was just making an excuse for his bad language.
.
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Native English teacher at Mister Micawber's