Use the snippet below to generate a random MAC address and assign it to your Wifi interface.
#!/bin/sh -e
mac=$(printf '00:60:2F:%02X:%02X:%02X\n' $[RANDOM%256] $[RANDOM%256] $[RANDOM%256])
sudo /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -z
exec sudo ifconfig en0 lladdr "$mac"