Origins: the infamous Crystalwank of FandomWank.
A popular
internet catchphrase used to sarcastically denote obvious falseness or lying.
The full original quote, "MY HED IS PASTED ON
YAY", comes from the above FandomWank thread wherein a LiveJournal user named Crystal attempted to convince her readers that she was real-life
friends with a cast member of the Lord of the Rings films by making very obvious photo-manipulations of the actors in various poses in her room. These photos were quite clearly pictures of the actor's heads transposed onto different bodies.
The thread became monstrous in a very short
time, eventually receiving over 13,000 comments. In the course of the thread, a commenter remarked that one of Crystal's photos wore a look of 'OmG my
head iz PASTEDE ON
YAY!!1111!!' The remark quickly spread across the
Internet, where it was adopted and adapted. This FandomWank thread, especially the "pastede on" comment, is considered something of a Holy Grail of internet slang.
See also pastede, my hed is pastede on, yay.
Since the initial wank, anything may be regarded as "pastede on
yay". A bad writer can be accused of having his/her spelling (or grammar, or ideas) "pastede on
yay!" A fruity drink that does not taste particularly fruity might be said to have its "fruitiness pastede on
yay!"