#!/bin/bash

TODAY=`date +%j`
CHRISTMAS=`date -d 25-Dec +%j`

til=("days til" "days until" "shopping days until")
pre=("There are" "Only" "Just")
xmas=("Christmas" "Xmas")

echo "${pre[$RANDOM % ${#pre[@]} ]} $(($CHRISTMAS - $TODAY)) ${til[$RANDOM % ${#til[@]} ]} ${xmas[$RANDOM % ${#xmas[@]} ]}."