Boeing KC-135 Stratotanker. Four engine USAF cargo plane designed for refueling other planes in flight. Based on the 707 airframe. A play on T. Rex, refers to the dinosaur-like age of the aircraft. See also Stratofortress Rex (B-52)
The USAF uses the Stratotanker Rex as a force multiplier. Isn't that bird 60 years old? Sure, but it still works.