Why is 'Justin makes us wet' trending?

At first we assumed that Justin Bieber’s fans were responsible.  But, no. Virtually all of the  “Justin makes us wet” tweets are from critics:

https://twitter.com/#!/sophiecooper/status/191481105118011392

https://twitter.com/#!/biIliejean/status/191481151192436736

https://twitter.com/#!/Callieox/status/191482442677358592

https://twitter.com/#!/Flashplumbs/status/191482440462766080

https://twitter.com/#!/BonnBBB/status/191481479392542721