Jump - Andrew Scott

1 - Go to where you customize your tumblr ( tumblr.com/customize ) and click 'Edit HTML'.
2 - Paste the following code anywhere after "<style type="text/css">" but before  "</style>"

        #jumpandrewpop {
	    left:0px;
	    bottom:-1px;
	    position:fixed;
	    z-index: 99; }

3 - Then paste this code right after  "<body>" (before  "</body>")

<div id= "jumpandrewpop"><a href="http://munchmeincookeh.tumblr.com/post/88900336090/"><img src= "https://38.media.tumblr.com/afdaffd48d3e676f47ba8dea5f829cce/tumblr_n78ff9Ig7X1toz38ro1_500.gif" height="375px"></a></div>

Tips: If the pic is too big or doesn't fit, change the value of 'height' for a smaller one (e.g.: 200px).
If it isn't working try erasing and writting the "}" again. Or just send me a message. Enjoy~