corner case
unusual
unwontedly
anomalism
unlikelily
unusually
change-up
kettle of fish
freak accident
problem
uncharted water
out of the common
exceptionably
hypo
surprise
accidentally
quaint
by chance
bizarrerie
weird
anomalous
big if
antrin
unexpectedly
singularly
unlikely
seld
funny
unusuality
aberrationally
semirare
oddment
plunder
as if by magic
atypical
isanomal
freak
rare as a four-leaf clover
rareish
queer as a clockwork orange
remarkable
one in a million
unexpected
eventuality
exotic
unusualness
noneven
how-do-you-do
unexpectingly
out of the way