Pulling your leg.
[Slang] PULLING YOUR LEG. - Explore the Fun Behind Pulling Someone’s Leg
Joking or teasing.
When someone is "Pulling your leg," they aren’t actually tugging on your limb. Instead, it’s a playful expression used when someone is joking, teasing, or trying to fool you in a friendly manner.
Example Sentences
I'm just pulling your leg, I didn't really forget your birthday.
The speaker admits to joking about forgetting someone's birthday.
Don't get mad, I was only pulling your leg!
The speaker tells someone not to get mad because they were only joking.
Relax, I'm pulling your leg; your car is right where you parked it.
The speaker reassures someone that they are joking and their car is actually where it was parked.