The phrase "spank you" is often used as a humorous and lighthearted alternative to "thank you." The pronunciation of this phrase is identical to "thank you" except for the initial consonant sound. The IPA phonetic transcription for "spank you" is /spæŋk ju/. The sound /sp/ is created by bringing the lips together and then quickly releasing them, followed by the sound /æ/ which is produced by opening the mouth slightly with the tongue low in the mouth. The sound /ŋk/ is created by bringing the back of the tongue up to the soft palate, and the final sound /ju/ is produced by rounding the lips and raising the middle of the tongue.
The phrase "spank you" is a playful variation of the phrase "thank you" which is used to express gratitude or appreciation. While "thank you" has a clear etymology, tracing back to Old English and ultimately derived from the Proto-Germanic word "thankōną", the phrase "spank you" is a humorous alteration of this expression.
The introduction of "spank you" likely emerged as a playful and humorous twist on "thank you". The alteration can be understood as a creative linguistic play on words, where the "th" sound is replaced with the similar-sounding "sp" sound, transforming "thank" into "spank". This playful substitution results in a colloquial and humorous expression, often used jocularly or in a lighthearted manner to evoke laughter.