Two aliens (the space kind) landed in the Arizona desert near a gas station that was closed for the night. They approached one of the gas pumps and the younger alien addressed it saying, "Greetings, Earthling. We come in peace. Take us to your leader."
The gas pump, of course, didn't respond.
The younger alien became angry at the lack of response.
The older alien said, 'I'd calm down if I were you.'
The younger alien ignored the warning and repeated his greeting. Again, there was no response. Pissed off at the pump's haughty attitude, he drew his ray gun and said gruffly, "Greetings, Earthling. We come in peace. Take us to your leader or I will fire!"
The older alien again warned his comrade saying, 'You probably don't want to do that! I really think that will make him mad.'
'Rubbish,' replied the cocky, young alien. He aimed his weapon and opened fire. There was a huge explosion. A massive fireball roared towards him and blew the younger alien off his feet and threw him in a burnt, smoking mess about 200 yards away in a cactus patch.
Half an hour passed. When he finally regained consciousness, he refocused his three eyes, straightened his bent antenna, and looked dazedly at the older, wiser alien who was standing over him shaking his big, green head.
'What a ferocious creature!' exclaimed the young, fried alien. 'He damn near killed me! How did you know he was so dangerous?'
The older alien leaned over, placed a friendly feeler on his crispy friend and replied, 'If there's one thing I've learned during my intergalactic travels, you never mess with a guy who can loop his penis over his shoulder twice and then stick it in his ear.'

Well you could certainly know who was best man at a wedding.