I think what the parent is saying is that these English word nonce generators are far more likely to use the word “house” and “fork” than it is to use “onomatop

I think what the parent is saying is that these English word nonce generators are far more likely to use the word “house” and “fork” than it is to use “onomatopoeia” or “fuck”. Thus, limiting the range of words likely to be used, leading to more easily guessed phrases. Also, I could be as thick as you ;).