Ok did some research here's what I found.
Turns out way back before they picked the names in 1A Horikoshi picked a hero name for Bakugo but then scrapped it. This name became a major headcanon for the Japanese fandom of BNHA which would all use it when refering to Bakugo and/or his hero name and this name was 爆心地 (Bakushinchi) which when translated to English means Hypocenter or Ground zero.
And wouldn't ya know when everyone got to picking their hero names Bakugo was named Ground Zero.
Side note:
Ground zero/Hypocenter is the point on the earth's surface directly above or below an exploding nuclear bomb.
Thanks sooo much! After I asked the Q I actually went online to check it. Guess it's just headcanon :( The names really cool though so I kinda hope he'll change it to that (≧∀≦)
Why is Bakugo's Hero name Ground zero? I don't remember him choosing it in the manga.