This achievement was proposed in the past, but has been rejected, because it raised littering concerns and failed to convince the community. Please read the discussion page for more details.
As per the page proposed achievements
: If an achievement has strong opposition and the reasons for opposition are not resolved through discussion, then the proposed achievements category is replaced with the rejected achievements category, the reason explained succinctly on the page, and the page otherwise marked to make sure it isn't confused with an achievements page.
This achievement is earned when you decorate the closest tree to the hashpoint in a suitably festive manner - for example with Christmas baubles and decorations in December. The tree must be within line of sight of the hashpoint, within the circle of uncertainty of your GPS, and you must choose the closest tree.
Bonus points for lighting the tree.