The spelling of the word "f gun" may seem unusual, but it is actually a phonetic transcription of the commonly used expletive. The "f" sound is represented by the letter "f," while the "g" sound is represented by the letter "g." The small space between the two letters is added to indicate a brief pause between the sounds. In IPA phonetic transcription, "f" is represented by the symbol /f/ and "g" is represented by the symbol /ɡ/. Therefore, the phonetic transcription of "f gun" would be /fɡʌn/.