I drew this while binging myself into the wee hours on Derpibooru. This idea was too funny not to draw.
 

 
After a particularly grueling Wonderbolts show, Rainbow Dash and Spitfire decide to have a romantic moment in one of the famed hot springs on the edge of town, heated by underground Dragon lairs. Even Pegasus muscles can get very bent out of shape from all those high-speed maneuvers…
 
Derpy joins in after a late-night special delivery run, making the Wonderbolt couple rather self-conscious. It’s hard to get intimate with a mare when you have another pair of eyes nearby, derped or otherwise. Then, as if that wasn’t bad enough, Derpy smiles warmly as she unintentionally turns the spring into a jacuzzi. Even at rest can Derpy derp things up…