Side note, another possibility that just came to my mind is Launching Day -> Raunchy Day, which is closer in pronunciation for those who live west of the pond (note: lance is pronounced differently in AmE and BrE). Doesn't have as much bite though.
Nanodesu!!Let's celebrate this eventful day with lots of fanfare!Ewwww!!Nanodesu!?Congratulations!!"Lanced", she says!?B-by whom?"W-Whose?" in the original. See following TN note.May 7 is the day when I, Akatsuki, was lanced!!bluuuuushEh!? I-I didn't slip up!! I did pronounce it properly as "launched"!!Aww, you can't help it.LancedHawawawawa!She meant "launched", right? That "lanced" must've been a tiny slip of the tongue.
Original has Akatsuki mispronouncing "shinsuibi" (Launch date for ships, analogous to a shipgirl's birthday) as "Chinsuibyo", which can be interpreted as "dick-sucking day".