Those words a not synonyms (synonym is not a synonym for cinnamon and grammar is not a synonym for Granma).
A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word.
The meme you posted is a play on similar sounding words.
A malapropism (/ˈmæləprɒpɪzəm/; also called a malaprop, acyrologia, or Dogberryism) is the incorrect use of a word in place of a word with a similar sound, either unintentionally or for comedic effect, resulting in a nonsensical, often humorous utterance.
Homophones are words that sound the same but are different in meaning or spelling.
For example this idiot uses the word "oranges" instead of the correct word "origins".
Don't be a bore, mate. The meme is supposed to be funny. If you don't find it funny, fair enough. Move on.
@Ryo1 I said that the meme you posted is unintelligent. If you created the meme or refuse to see the error in the meme then you don't have the intelligence of a 10 year old who has learned how to use a synonym correctly.
The meme is not funny because it makes no sense. It doesn't mean what the meme creator intended for it to mean. It's just a play on words, a malaprop, which nullifies the supposed joke.