Calculate the date of the $(random number between 1 and 31) of $(random month) $(random year between 1970 and 2020)
cal $(shuf -i 1-31 -n 1) $(echo {Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec}|shuf -n 1) $(shuf -i 1970-2020 -n 1)