By Aly Semigran, Hollywood.com Staff

While the rest of the nation celebrates Memorial Day with a bevy of BBQs, Justin Timberlake and Jessica Biel attended a different kind of bash this weekend: Their engagement party.

People reports that the incomprehensibly beautiful couple attended a cocktail party in Los Angeles on Saturday for their impending nuptials thrown by Biel's stylist. Among friends and family who attended were famous pals like Ellen DeGeneres, Amy Adams, Timberlake's 'NSYNC band mates JC Chasez and Lance Bass, and his collaborator Timbaland, who made a speech to toast the happy couple. (You know what's cooler than a Timbaland speech? A billion Timbaland speeches.)

The couple, who got engaged back in January after an on-and-off courtship, partied and danced through the night before they left at 12:30 in the morning. (The deejay reportedly played classics like Madonna's ""Holiday"" and Whitney Houston's ""I Wanna Dance With Somebody,"" though curiously, not Timberlake and Andy Samberg's SNL sensations ""D**k in a Box"" or ""Motherlover."")

A source told People that Timberlake, 31, and Biel, 30, who will reportedly tie the knot this summer, ""looked very happy"" at the affair.

[Photo credit: WENN.com]

More: Justin Timberlake and Jessica Biel to Wed This Summer Justin Timberlake Composing Music for Jessica Biel's New Movie'NSYNC Reunion Not Happening, Says JC Chasez

Justin and Jessica engagement