So, I finally decided to come up with something a bit more "original" for those people who bother me:
A - Are
B - Bee
C - Cite
D - Double-U
E - Eye
F - Five
G - Genre
H - Hoe
I - I
J - Junta
K - Knot
L - Lye
M - Me
N - Nine
O - Owe
P - Pseudonym
Q - Queue
R - Rap
S - Sea
T - Tsunami
U - Understand?
V - Vie
W - Why
X - Xylophone
Y - You
Z - Zero
People don't ask me to spell anything over the phone anymore.