That’s Not What He Meant!
If you watched Justice League, you probably were too little to understand everything. The Flash is the fastest man alive and was proud of the fact, and there is an episode where the Hawkgirl tells him that the fact that he is so fast is why he cannot get a date.
Source: Twitter
She meant that Flash’s love life was a mess because he was too fast in the bedroom, which got to him as it was written all over his face. We didn’t get this joke as kids as we had no idea that being so fast could be a bad thing in another context!