Is this really an insult? （こもち ししゃも）

He Says:
komoti sishamo　（こもち　ししゃも） is kind of a funny word.
Originally,kimoti means pregnant, sishamo is a smelt,one of fish.
So a pregnant smelt has so big stomach.
But we japanese use the word for the calf of people.
Some people have so big calves because they exercise much or something.
Then some of Jp say,"they have komoti sishamo in their calves!"
Sometimes I can see people whose calves look like pregnant smelt.
They look they have 2 pregnant smelts in their calves.
But this word is irony,or bad word, so if you say it to jp girls,you know what happens then!?

She Says:
This doesn't translate so well. I don't get it, even after extensive explanation from Him. It just doesn't seem funny or insulting or anything like that to me. I mean, we're not talking about cankles or anything like that...just muscular calves.
I suppose it plays into the idea that women aren't supposed to be muscular at all? But any, I don't really get it.

The next word is...めす　ぶた。