party.sh

function party {
  if ! command -v figlet; then
    if ! command -v brew; then
      echo Requires figlet or brew to be installed
      return 1
    fi
    brew install figlet
  fi

  if [ -z "$1" ]; then
    echo "Enter party word: "
    read PARTY_WORD |  tr '[:upper:]' '[:lower:]'
  else
    PARTY_WORD=$1
  fi

  if [ -z "$2" ]; then
    echo "Enter party word emoji (without colons): "
    read WORD_EMOJI
  else
    WORD_EMOJI=$2
  fi

  if [ -z "$3" ]; then
    echo "Enter background emoji (without colons): "
    read BACKGROUND_EMOJI
  else
    BACKGROUND_EMOJI=$3
  fi

  echo
  figlet -f banner $PARTY_WORD | sed -e "s/#/:$WORD_EMOJI:/g" -e 's/^/ /g' -e "s/ /:$BACKGROUND_EMOJI:/g"
}

credit to dpowell

I got this working on Ubuntu 16.04 by changing the first part to:

  if ! command -v figlet >/dev/null; then
    if [[ "$(uname)" == Darwin ]]; then
      if ! command -v brew >/dev/null; then
        echo Requires figlet or brew to be installed
        return 1
      fi
      >&2 echo "Installing figlet..."
      brew install figlet
    else
      >&2 echo "Installing figlet..."
      sudo apt-get install figlet
    fi
  fi

Bonus: I redirected command -v figlet and command -v brew STDOUT to /dev/null so that e.g. /usr/bin/figlet doesn't get printed out along with the figlet output, so I can do party foo bar baz | pbcopy to copy the output straight to my clipboard.