Question: I learned British English, but I work exclusively with Americans. I'll often say "Fat lot of good X did for us", and I get confused looks from others. For example, the other day, I said "I think we should have had them take the web development course; fat lot of good the algorithms course did for them" and people have no idea what I mean. A coworker told me that what I'm saying sounds like what someone British would say, and I'm not sure how to Americanize this statement.

First: Am I using the term "Fat lot of good" incorrectly? Second: How should I say this in American English?

Answer: 
**Just leave out the fat**, in speech, and use a sarcastic tone.

"I think we should have had them take the web development course; a lot of good the algorithms course did for them."

The fact is that this is an idiomatic expression.

And **many Americans** *would in fact understand*
"a fat lot of good". Who cares what a coworker says? The expression is not essentially British at all.

It's in Merriam Webster like this:

a (fat) lot of good
idiom
informal
: no use or help at all
"I've brought an umbrella." "A (fat) lot of good that will do now that it's stopped raining!"

[Merriam Webster](https://www.merriam-webster.com/dictionary/a%20%28fat%29%20lot%20of%20good)
A whole lot of good would also work. I'm guessing the confusion comes from the fact that "fat" generally refers to being overweight.