There's surely a pun but I don't get it. It looks like Nazrin is copying a famous song or something but my culture is pretty limited, when it comes to Japanese songs.
Here's a fast translation anyway.

"...since I'm Nazrin."
"That's the best reason I've heard for anything all day."

Alternatively, you can just end all your sentence with "since I'm Nazrin" to sound insane, since I'm Nazrin.

Marisa stole the precious thing joke?

Maybe, since I'm Nazrin.

I support the adoption of this new meme, since I'm Nazrin.

I favoured this comic, since I'm Nazrin.

Hmm, maybe this is from Yakitatte Ja-pan where there's this contest judge that's a pierrot that keeps making impossible feats and ridiculous decisions, when people all go wtf he just responds with "since I'm a Pierrot~".
Of course I could be mistaken about it, since I'm Nazrin.

Nazrins clothes defy gravity in comic panel two

Torqueware said:
Nazrins clothes defy gravity in comic panel two

Since she's Nazrin.

Added to favorites, since I'm Nazrin.

ao usagi is awesome, since I'm Nazrin.

I've wandered in randomly, since I'm Nazrin

ITT silly people forcing a meme.

Lepperchaun said:
ITT silly people forcing a meme, since I'm Nazrin.

Fixed, since I'm Nazrin.

So popular, Littleshrimp is referencing it, since I'm Nazrin.

You're all posers, since I'm Nazrin.

Posting a comment, since I'm Nazrin.

I dont get it, but I still laugh at this, since I'm Nazrin.

C-C-C-COMBO BREAKER!!!, since I'm Nazrin.

I find it completly mad, but I laugh anyway, since I'm Nazrin.

I sometimes wonder what happens to the people whose brains Ao Usagi breaks... since I'm Nazrin

But then I look in here and it makes sense, since I'm Nazrin

Nazrin , since I'm Nazrin .

Carrot, since I'm Nazrin!

I lol'd, since I'm Nazrin!

I knew that this would start a new meme... since I'm Nazrin!

I'm just hoping the same accident wont happened again

like here post #627836

since I'm Nazrin

we need a tag for this, since I'm Nazrin

I want to see more comics with this new meme, since I'm Nazrin.

I wish I could punch people in the face via TCP/IP.

This joke is getting too old......Dahil ako ay si Nazrin.

博麗 said:
I wish I could punch people in the face via TCP/IP, since I'm Nazrin.

Fixed, since I'm Nazrin.

Are we starting another failtrain here?

Come on guys, you better stop now before the Admins/mods start suspending people, again.

But ナズリンだけに doesn't mean "since I'm Nazrin"…

what does it mean, then?

Well, だけに, as a conjunction, can mean "Because". So it should really say "Cause I'm Nazrin!"

It's so great, since I'm Nazrin.

I had no idea Usagi made this, but it looks fairly normal for him, since I'm Nazrin.

memento_mori said:
But ナズリンだけに doesn't mean "since I'm Nazrin"…

JakeBob said:
Well, だけに, as a conjunction, can mean "Because". So it should really say "Cause I'm Nazrin!"

Really? Is that so? That's interesting... I resisted! Hahah!

This reminds me of the ceiling cat.

This reminds me of the ceiling cat.

Akazuma said:
This reminds me of the ceiling cat.

Since you're Nazrin?

I thought the comic was funny, since I'm Nazrin.

Lepperchaun said:
ITT silly people forcing a meme.

Isoceles Triangle Theorem?
Oh well, whatever, since I'm Nazrin.

Featured on Tv Tropes, since I'm Nazrin. As well as the part of how everyone is sick to death of it Since I'm Nazrin

Never heard of it before... huh, since I'm Nazrin, probably?

So being Nazrin allows you to steal food from Reimu without being instantly killed?

angrybull said:
So being Nazrin allows you to steal food from Reimu without being instantly killed?

Obviously since she's Nazrin! Do not underestimate the power of being Nazrin.

Keo said:
Come on guys, you better stop now before the Admins/mods start suspending people, again. Since I'm Nazrin!

Dogenzaka said:
Are we starting another failtrain here? Since I'm Nazrin

Folt said:
Really? Is that so? That's interesting... Since I'm Nazrin...

-maniac laughter, since I'm Nazrin!-

I find this 'meme' somewhat humerous, since I'm Renya.I bet you expected Nazrin, since I'm Nazrin, didn't 'cha?

Is this the origin of "since I'm Nazrin"?

ithekro said:
Is this the origin of "since I'm Nazrin"?

Seems so, at least TH wikia says so. If it's used in other posts (rather than in comments only), this should probably go to "origins" pool.

Type-kun said:

Seems so, at least TH wikia says so. If it's used in other posts (rather than in comments only), this should probably go to "origins" pool, since I'm Nazrin

Fixed, Since I'm Nazrin.