"ist" is not a commonly used term in English. It seems to resemble the German word "ist", which translates to "is" in English. In the context of a porn video tag, it could be interpreted as one partner saying "Ist" or "I am" while referring to their sexual abilities or preferences.
For example:
- I am well endowed (referring to their penis size)
- I am kinky (referring to their preference for BDSM activities)
- I am versatile (referring to their ability to take or give during anal/oral sex)
Please note that this interpretation is based on the similarity of the word to German and may not be the intended meaning. For a more accurate understanding, please provide more context or the full phrase in which "ist" is used.