How can I make this funny story better? Please correct any spelling mistakes, words, etc.This is embarrassing story of my mom when she was...

First of all, you need to read your story aloud which
should help you hear the missing words such as the "an" which belongs after "is" in the
first sentence.  Too many of your sentences start with pronouns which give you no power,
and so many short sentences could be combined into one better sentence.  Vary the length
of your sentences, and do more "show not tell".  For example, how was your mother doing
a great job?  Was she smiling, eating with the correct fork, not spilling her food?  Set
this up with more pictures of what was happening before the joke.  Who else was there at
the table as you say only the two people laughed?  Did she say anything before going out
onto the balcony?  Remember, when you write a story for effect, you can embellish a
little for dramatic effect.  Decide which details would help create a build-up to the
climax of the story and then use them.