be mustard at

e.g. I am mustard at parallel parking.

Dose this phrase have the same meaning as "be good at" in this situation?
Is this a common expression in English conversation?
I looked up the word "mustard" in my dictionary, but I couldn't find any similar phrase or idioms there.

Thanks for your help in advance!!
Hi Candy,
I have never heard 'mustard' used this way, but there is an idiom 'keen as mustard' which means astute or 'on the ball'. There is a British mustard making company called Keen's, who probably popularised that idiom.
Bearing in mind that mustard may be considered by some to have a bitter taste, it's also possible that it means 'bad'
So take your pick, good or bad! Confused?
Don't worry, no doubt someone else who uses the site and has heard 'mustard' used this way will 'shed light' on your 'tangy' question!
Maybe I could pass muster at parallel parking?
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 Mike in Japan's reply was promoted to an answer.
Thanks for your reply Emotion: smile

Here is the context for this sentence;

Resisting the urge to execute a handbrake turn into it, I enthusiastically parallel park (I am mustard at parallel parking).

So, in this situation, it means 'I have a hard time to parallel park' or 'I am terrible at parallel parking,' maybe!?
Ah... if the writer can execute handbrake turns they are quite a skilled driver! With this knowlege I would think they are also capable of accurate and fast parallel parking.
So I would think that in this case it means "I am great at .....
P.S. If you have never tried a handbrake turn but want to, please do it in someone elses car and not your own. It's a lot of fun, but a trifle risky.
Good luck Candy!
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Now I understand what "handbrake turn" is Emotion: smile
Thanks for your advice for it.
When I try a handbrake turn some time in the future, I'll ask someone else for the car.
Ah....actually, I tried it before, so I know how risky (but sometimes great) it is!!