Hmmm. I checked the XBL
http://www.spamhaus.org/query/bl?ip=64.237.48.160
As you can see... no listing. XBL is realtime so this should be current.
But they say:
"If the IP you are checking is not in our database, but you are receiving bounce messages saying it is, then it is probable the IP has been removed from our database but DNS servers around the internet have not yet updated. In this case, wait 1-2 hours and the blocking should clear by itself."
Looks like hahahahahaha is in SPEWS though and a few others:
http://openrbl.org/ip/64/237/48/160.htm