Kendrick Lamar just dropped his new song "The Heart Part 4," and he takes aim at an unnamed rapper on the second verse. To catch you up to speed, here are the lyrics in question:

"My fans can't wait for me to son your punk ass and crush your whole lil shit
I'll Big Pun your punk ass you a scared lil bitch
Tip-toeing around my name nigga you lame
And when I get at you homie don't you just tell me you was just playin
'I was just playing K-Dot, c'mon you know a nigga rock with you bro'
Shut the fuck up you sound like the last nigga I know
Might end up like the last nigga I know
Oh you don't want to clash? Yeah nigga I know"

And later:

Hoe, Jay Z hall of fame, sit your punk-ass down
So that means you ain't bigger than rapping

So who could it be? If we're going off who has potentially taken veiled shots at Kendrick in recent times, it would be Big Sean, who rapped this on "No More Interviews":

And I can’t lie like I like this shit like I usually do
And I’m just not impressed by you niggas rapping fast
Who sound like one big asthma attack but trash when I’m rapping it back
Who you put in your top five and claim they the savior of rap

Note the "big asthma attack but trash," which many pointed to as a reference to Kendrick's delivery throughout untitled unmastered. 

On DJ Khaled's "Holy Key," which also features Kendrick, Sean gets off these bars with a flow similar to K-Dot:

Woah, I hear a little bit of me in all your favorite rappers
You know it's true, bitch I need respect due

If we're stretching back a few years, Sean also had these lines on "Me Myself & I (Freestyle)":

Rappers who was killin shit, lately I can't feel that shit
Y'all used to didn't feel my shit and now y'all like, "You hear this shit?"

But let's circle back to Kendrick's lyrics on "The Heart Part 4." He uses the term "lil" more than once, then claims he will "Big Pun your punk ass," which could be a flip on Big Sean's name. "Tip-toeing around my name" could be in reference to the Sean lyrics above, especially "No More Interviews."

Let's also take into account Kendrick rapping "lil bitch," which is one of Sean's favorite ad-libs: 

Then consider the line where Kendrick raps from a different perspective ("I was just playing K-Dot, c'mon you know a nigga rock with you bro"): the cadence of the voice sounds kind of familiar, don't it?

Finally, the reference to "hall of fame," which was the title of Big Sean's second studio album, along with a mention of "bigger." 

If you know Kendrick, you know he rarely wastes lines, and when it comes to stuff like this, he's shooting for a reason. It'll be interesting to see how this plays out. 

And like always, Twitter was on fire: