Boot Camp Reply is a term used to describe the response given by a recruit in the military when addressed by a superior. The three most common responses are SIR (3 letters), NOSIR (5 letters), and YESSIR (6 letters). SIR is an acronym for 'SIR, Yes SIR' and is used to show respect and obedience to a superior. NOSIR is an acronym for 'No SIR' and is used to politely decline a request or order from a superior. YESSIR is an acronym for 'Yes SIR' and is used to affirm a request or order from a superior.