curl -s https://www.floobits.com/ | head -c15 | tr "[:upper:]" "[:lower:]" | tr -d "\n"

Send a request to the Floobits website, take the first 15 characters, convert all uppercase letters to lowercase, and remove the newline character.
curl -s https://www.floobits.com/ | head -c15 | tr "[:upper:]" "[:lower:]" | tr -d "\n"