From which song did System of a Down nick the lyrics?

[Sarahmitz]

Please (x100) can someone help. I know I'm not mad, System's BYOB, has the lines "going to a party, sure to have a real good time.." I knew those lyrics & tune as soon as I heard them, but the song eludes me. I think it may be a 70's funk band but I have googled extensively over the past 6 months.. Please someone should know to prove I'm not going mad. If you get the answer I'll not only buy you a virtual pint but a virtual pub,
Thanks.

[237SJ]

Is there anywhere we can listen to the song? Is it on itunes? (the System one I mean)

[237SJ]

I`ve just listened to a bit of it on last.fm. I know the bit you mean and the tune sounds familiar but I don`t think those words went with that tune in any original song. It`s almost on the tip of my tongue and is doing my head in now. I was going to go to bed as well. I`ll have a think

[Sarahmitz]

Thankyou for your devotion to trivial music questions. I've been feeling like you for 6 months. Hope you get a good night's rest. If you get a spark of inspiration I'll buy you the virtual pub.
Thanks,
Sarahmitz

[237SJ]

One nation under a Groove by Funkadelic? Tune`s the same but not the words as I said Is the Dom Perignon in the post?

[Sarahmitz]

This song was so close to the mark. I was so disappointed when it was wrong. My gut (not me) think it is a funky tune.... Lets solve this problem!!! Remember ... "Going to a party,sure to have a real good time". I am going toward 70's funk but could be so very wrong. Help!"!!!! I'm going nuts.