Twilight never had any qualms airing out the girls in front of Spike, her friends, or even total strangers. Be it in the comfort of her home or out in town, Twilight proudly displayed what the Spirit of Harmony gave her. Even after becoming royalty, Celestia often had to get on her hands and knees and beg Twilight to simply put on a bra for when the less open-minded diplomats visited.
 
Needless to say, many stallions and mares had their first experience cranking it to Twilight’s enviable body.  
There’s also a persistent and concentrated rumor that she will drop to her knees and give a tittywank to those furthering the ideals of Harmony, and continue about her day with the ensuing seed still on her chest.