For a good few years now, Vinh has always been a master of surprise. 

People have questioned time and time again how Charisse couldn't have possibly "seen it comin',"

but truth be told... every relationship milestone for this happy couple has resulted in some elaborate production of sorts on Vinh's part,

so Charisse really didn't expect that this was going to be any different, much less,  "the big one."
On July 17, 2012 (The 4 year anniversary of the day the lovebirds met) Vinh arrived at Charisse's house donning a tux and carrying 2 dozen long stem red roses.

A town car arrived to whisk them away and Vinh asked Charisse to wear a blindfold, so that she couldn't figure out where they were headed.
They arrived at the California Science Center (Between USC and the Coliseum),

and he escorted her to the center of The Robert H. Lorsch Family Pavilion, golden star foyer -- this is also known as their "kissing spot"

(their tradition is to kiss in the center of the pavilion every time they pass... sort of like how Trojans kick the flagpoles en route to a football game)
When he removed her blindfold, the USC SoCal VoCals began an a cappella arrangement of their song, "1234" by the Plain White T's.
During the instrumental, Vinh led Charisse into the center of the marble star-map platform,

filled with red rose petals in a heart of votive candles.  He got on a knee and popped the question.
She cried.  Of course, she cried...

but somehow amidst the tears of joy managed to say "yes," and even ended up on her knees as well. 

Not too over the top, not underwhelming...  for Charisse, at least, it was an unforgettably amazing, absolutely perfect night.