I had three ideas and finally did this one.
Twilight, the inspiration of Twilight Sparkle. As G1 ponies are generally more horse-like and the act of licking being a horsey thing, poor Sparkle has to endure it. She doesn’t want to upset her ancestor, though, a princess knows how to endure that. I heard that she tastes Twilicious.
In case you have issues to read the text:
“Ugh! Old ponies and their odd habits!”
(Credit to Nyerguds for that line.)
I planned to do this last weekend, but I got seriously sick on Thursday evening and haven’t fully recovered yet. Unable to use the daylight due to chores during the day, I had to draw it with my laptop’s screen light. My improvised art space has no light source other than daylight. Derp.
I still did it, yay. But no way I could colourise it before the deadline in the remaining time and in these conditions, nay.
Coloured Version: