This bug is found by Indrajeet Bhuyan , he found that sending more than a couple of Smileys ( Say 4000+ ) will crash anyone's Whatsapp due to " overflowing the buffer " .
Here's How to Crash someones's Whatsapp with Smileys ( For Educational Purpose only ) -
Step 1. Open web.whatsapp.com via Mozilla firefox ( PC / Mac ) .
Step 2. Login to Web Whatsapp ( Just Scan the QR code given on the desktop screen through your Smartphone's Whatsapp app ) .
Step 3. Now Choose a Target ( Open chat of any of your friend ) .
Note - Ask him to take a backup of Whatsapp , as now his /her Whatsapp is going to crash .
Step 4. Now Start typing 4000+ Smileys ( Do Copy paste , but don't copy more than 100 smileys ) .
Step 5. Send it ! Now your Browser will stop responding ( Just wait ) .
Watch the video for full procedure -