Someone I know IRL went to the florist and picked out a bouquet to have delivered to her dh at work. She took the HPT and attached florist wire to it (with florist tape--she had to do it herself because of the bodily fluid factor, but the florist was happy to accomodate her) and stuck it down in the bouquet among the flowers. Then just wrote "I love you, hope you are having a great day!" on the card and had it delivered. It took him awhile to even find the HPT, then took him awhile longer to figure out what it was, and what it meant, LOL!
Me, I'm way too impatient to come up with surprises for dh....and usually way too shellshocked, LOL! Besides which, by the time it occurs to me to test, he has already figured it out! Every time! He needs to start sending ME flowers with (unused) HPT tests in them!
Congrats to your friend--I hope her dh is thrilled, no matter how she tells him!