Do pilots say ready for takeoff? There is no specific, defined procedure or phraseology for the pilot. In practice, the pilot will typically say something like “Tower, N123 is ready to go”, “ready at [runway] 25 Left”, “ready for takeoff”, “ready for southeast departure”, etc.
(In 1957, the English phonetic alphabet changed the R to Romeo, but by that time, Roger was deeply embedded in the minds of pilots.) So, in short, Roger means r which stands for received. The word Roger means nothing more.
Pan-Pan, short for “possible assistance needed,” is used to communicate an urgent, but not emergency, situation over VHF radio, in the case of aviation, to air traffic control. Examples could include a recreational pilot getting lost, or perhaps needing to climb to a higher altitude to sort a problem out.
The call sign is a specialized form of nickname that is used as a substitute for the aviator's given name. It is used on flight suit and flight jacket name tags, painted/displayed beneath the officer's or enlisted aircrewman's name on aircraft fuselages or canopy rails, and in radio conversations.