The new WhatsApp Glitch

May 04, 2018

You may have received a message like this recently 

  
  If you touch the👇black point then your whatsapp will hang

  ⚫ 👈🏻 t-touch here
... and once you touch the black button emoji on an Android phone, your WhatsApp will probably hang. Just like the message told you.

Explanation

It's actually really simple: Besides the actual text, the message includes around 6000 (invisible) unicode characters 
  
  If you touch the👇black point then your whatsapp will hang

  ⚫<200e><200f><200e><200f><200e><200f><200e><200f><200e><200f><200e><200f>[...] 👈🏻 t-touch here
Those are normally used to indicate a left-to-right/right-to-left writing.
If you include an even number of them, the text does obviously not change the direction and that's what the "author" of that message did.
I'm not sure why it causes WhatsApp to crash but I guess it's just unable to process that many direction changes because it's loading them all into memory (which has a physical limit) or something like that.
Why ~6000?
Because 6000 is the limit where WhatsApp displays a "read more..." button and it's probably enough to fill the memory of most phones in use today.
Do it yourself
  
  # -*- coding: utf-8 -*-
  ltr = u'\u200E'
  rtl = u'\u200F'
  ltr_rtl = ltr + rtl
  print(ltr_rtl * 1000)
  
  
  $ python3 ltrrtl.py | xclip
  $ # all left to do is to paste your clipboard in WhatsApp Web
... or just copy the text from this textarea (click into it + press strg a + strg c) and insert it after any message.
Those are 2000 characters in total, so there's enough space left for a personal message