Used to suggest that something is slightly sick or malfunctioning, but not completely broken. I'm feeling dicky today, might be that food from last night.
Pro Tip 2/3
Subtle Warning
Indicates a potential future problem; a hint that something might need attention. Watch out, the weather's looking a bit dicky, so take an umbrella.
Pro Tip 3/3
Not Serious
Conveys a minor issue, not to be overly worried about, often passing or temporary. My laptop's been dicky this morning, keeps freezing.