"I'm off, see you tomorrow night!"
(No more than 60min. later)
ACHIEVEMENT UNLOCKED:
Onee-chan!
(Acquire younger sibling)
Funny thing,that,it can actually take a day or two for the sperm to actually achieve results(this is also why "safe days" are complete fantasy),whilst actually getting pregnant from one time is about 33%(if that one story about a sex ed teach who actually gave a damn is true),so you'd need get it on like Donkey Kong four times for a more solid gurantee.
Knowing these two rabbits,they'd get it done in 15 minutes and have the results in two days(albeit pregnancy tests need two weeks for actual confirmation).