In one of the posts, Fiddy superimposed the Notorious's head onto the body of Britney Spears in a photo of her during the infamous umbrella attack.
The caption read: "Is that you Britney. LOL."
Now, never one to take this kind of thing lying down, McGregor went in on his former ally and called him out.
Explaining the story behind their beef, McGregor said: "I'd have to probably say 50 Cent, I'd like to fight him.
"Throughout the course of the Floyd Mayweather build-up I used him as a tool, a promotional tool on the free also, I knew he was linked to Floyd so I tied him in also and he responded big time and capitalised on that audience so I was very thankful.
"But then after that he began a little tirade against me on social media, particularly Instagram where he'd make these memes about me constantly.
Proper No. Twelve Exclusive! @TheNotoriousMMA announces here who he would like to fight next! #OneForAll pic.twitter.com/YNHUrctBzu
- Proper No. Twelve (@ProperWhiskey) October 25, 2019
"Every time I'd go onto the internet I'd see 50 Cent had posted up some new stupid meme and I wrote on one of the memes - old man on the internet making memes - and then he blocked me.
"So he's had to block me, and I still see sometimes, I still get tagged in other people saying he's saying this and he's saying that.
He added: "So I'd like to have a knock-off with 50 yeah, so if you're listening 50, let's get it going bud."
But Fiddy ain't the only one the Dubliner has been getting a bit aggy with of late - of course not.
During the promotion for UFC 229 event, McGregor caused controversy when he offered a stream of verbal attacks on opponent Khabib Nurmagomedov. Because... well, Conor McGregor.
Surprisingly, some people didn't take too kindly to McGregor's apparent lack of respect for their national hero.
Then at a press conference which took place in Moscow earlier this week, McGregor continued with his comments, calling Khabib's father a 'quivering coward'. Taking aim at his rival's home city, he added: "I wouldn't go to Dagestan to take a s***, and that is the truth."
One Dagestani man was left particularly unimpressed by the comments, taking McGregor to task at another press conference on Friday (25 October).
According to The Sun, the man asked: "Do you remember what you say about Dagestani people yesterday? If you hate Khabib and his team, why do you say bad things about people?"
Conor began to explain himself, and can be heard on the video saying: "The disrespect they showed me in the build up to the fight, they sold items in the grocery with my face on it..."
The man - who has not yet been named - then responded: "All the people? My father, my brother, you think are all cowards? Why cowards? My father?! What did he do to you?! My brother, what did he do to you?!"
At this point, a bottle was launched into the air towards the Irishman.
But with McGregor announcing he would be returning to the octagon on 18 January 2020, we might have some wait before we see McGregor v 50.
However, if there are any developments, which is very possible with him, we will be sure to let you know.
Featured Image Credit: PA