#PMHT or Pardonmyhashtag can now not only be found across a wide range of social media, forums and netspeak, but it is also in most slang and urban dictionaries, and also becoming more commonplace in technical and general dictionaries too.
Slang or Urban dictionaries
The urban dictionary: http://www.urbandictionary.com/define.php?term=%23PMHT
Online slang dictionary: http://onlineslangdictionary.com/meaning-definition-of/pmht
Merriam Webster: http://nws.merriam-webster.com/opendictionary/newword_display_alpha.php?letter=Pm
Definition of: http://www.definition-of.com/PMHT
The ultimate compute acronym dictionary: http://www.acronyms.ch/files/Acronyms.A4.Simplex.pdf