Have you ever heard anyone saying, "it's a dog's dinner"? This phrase means that something is a complete mess, all jumbled up and confused, or is a poor piece of work.
"Your homework is a dog's dinner!"
"You look like a dog's dinner in that outfit."
"He tried to decorate the house but made a dog's dinner of it."
People often say, "You have made a (proper/complete) dog's dinner of it."
Please note, you must say, "a dog's dinner", and not "the dog's dinner" nor "the dinner of the dog"!
The next phrase is very common in speech and writing: to have your cake and eat it. This means that you want to do two things but one of them is impossible if you do the other. You want to have or keep your cake, and also to eat it, but clearly, you can't do both.
You can also say, "have your cake and eat it", with the verbs in a different order. I prefer this because it makes it clearer that you want both to keep the cake for later and to eat it now.
"They want to eat their cake and have it."
"You can't have your cake and eat it."
Finally, we have: "take the biscuit". This refers to something surprising or to something that is either the worst or the best. The meaning will depend on the context.
"She has done strange things before but that takes the biscuit."
"I have had three trains cancelled in a row - that really takes the biscuit."
"Well done in the competition! You took the biscuit with your entry." (won first prize)
Please note, you cannot say "bring the biscuit"!
Sometimes it is good to use colourful phrases as well as correct grammar, or at least to recognise them when you see or hear them.
A slice of lardy cake from The Indulgent Baker at 32d Church Street, Caversham, Reading, Berkshire, England By Smuconlaw - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=41649258