(http://fc09.deviantart.net/fs71/i/2013/081/b/a/wwe_tg_kane_undertaker_by_gagrewhtymnhgh-d5yxb9k.jpg)
...is the first result when looking for the Undertaker's "cameo" in Yu-Gi-Oh! GX.
Oh internet, you so silly.
Didn't know Vega and Snake were such buddies.