Well you can give it a try but i'd recommend you call on your cell phone saying following.
Her: Hello?
You: Whats up
Her: Nothing blah blah blah
You: Are you adventurous?
Her: Yes (see bottom for NO)
You: Well I'm in the area get dress and lets________ i'll be overthere in 5-10 mins.
Her: umm ok
You: Ok bye
Her: No
You: Thats too bad I had a big surprise for you.
Her: What.. What is it?
You: Na forget it (playful tone)
Her
lzzz
You: Ok i'm in the area get dress and lets_______
(The surprise could be anything, from a kiss too just her seeing you.)
Be able to calibrate so you won't be stuck on what to say.