R4 

In Reddit, especially on r/badX (like r/badmathematics or r/badlinguistics) subs, R4 is a comment placed after the post made by the same author to explain why the content linked by the post is bad, therefore it is suitable for that sub.

R4: Apparently OP believes that the operations you can do with a number based on how it was constructed. For example, they think that you can't "unsquare" 64 to get its square root if it was constucted by some manner other than squaring 8. At least as far as I can understand their post.

R4 by Xwtek December 26, 2021

R4 

Assault rifle of the South African army, developed in the country as response to the arms boycott during the 70'2 and 80's. Successor to the R1 of 7.62mm bore. Bore of 5.56mm. Extremely reliable in the field and maintained without tools. Equally suitable for left- and right handed shottists. Most popular method of cleaning the rifle was to chase 30 rounds through the barrel. Later followed by the R5 with more refinements.

The R4 compares extremely well with the M16 Assault rifle, and equals the AK47 in most repsects

R4 by Frank1e July 9, 2006

R4 

Another meaning for "or for"

''hey R4 you can use this for shit like that''

R4 by BleedingEars August 15, 2021

R4 

A popular shortcut for "Rinora 4", one of the biggest clubs in Switzerland. People from all over Switzerland travel to Zurich at the weekend to enjoy the ambience of the club. The club is known for its friendly bouncers.

Person A: Bro I just graduated Hustler’s University, let‘s celebrate that!
Person B: Hell yeah, R4 is the perfect place for that.

R4 by HakFather October 29, 2022

r4.nb00 

a very appreciative and friendly tiktoker. they go by she/they pronouns and are pansexual. their most liked tiktok is one with her wife.

person 1: Hey did you see r4.nb00s new tiktok?
person 2: yeah, it was the one with her wife!

r4.nb00 by r4.nb00 October 19, 2021

r4 card 

r4 card is a slot-1 flashcard for Nintendo 3ds, dsi and ds console. with a SD card, the r4 card can play games, video, music and other media files for totall free.

r4 card, r4i sdhc card, r4i gold card, dstwo, M3i zero,r4itt card, tt 3ds card,

r4 card by r4town.com June 23, 2013

r4.nb00 

A very swag and cool tiktok account with everything cool in life on it. They have over 1000 followers and at extremely awesome. THEY ARE VERY COOL AND HOT and also have a wife who loves them very much (@wasssspoppinggggg)

Person 1: Are you bored ?

Respon 2: yes
Person 1: check out @r4.nb00 on tiktok

r4.nb00 by wasssspoppinggggg October 20, 2021