intravaginal tongue
This tag refers specifically to when a tongue (not tentacle) is attached to the inside of a vagina, and is not part of the labia or clitoral hood. Not to be confused with other ambiguous tags such as 'pussy_tongue' that could be taken as a tongue with a vulva or vulva-like appearance.
Can be used to refer to anatomy where an anatomical mouth has replaced the character's vulva/vagina.