Being straightforward with those close to us

How do I work on being more straightforward. I was with kids and they said “we’re coming home with you” so as a joke I said to the 6 year old “okay whose driving are you gonna drive us there”. And then they started walking to the car. Then their mom told them we would have to plan something and it was a joke. I asked them where they want to go when we plan it and they told me the trampoline park. I agreed and said next time. But then when they asked if we could go tomorrow I again said okay tomorrow is it just so they could be happy. But then I realized that I need to be more straightforward cause their mom reminded them we will plan something then the 4 year old started crying that she wasn’t coming home with me so we can go to the trampoline park. Is it being straightforward that I need to work on or do I joke too much? I’ve had young ones in the past think I’m a liar because I joked this way and I guess I just don’t know how to handle that conversation of telling them no when they keep asking for something.