The deadly ass could be an ep about Rose Tyler.
In that one ep an entity imitating her form and appearance sat on a doomsday weapon detonator to keep Hurt's doctor from setting it off, and when he finally got her off it and tried to use it be pulled his hand back and yelled "It's hot¡"
She said in her sexiest tone "Well, I do my best... "
https://youtu.be/a8HoZlhenZ4