Threats you can't or won't follow through with.
Something I learned as a teacher and have tried to carry on through my parenting is to not threaten with taking away something that I don't want to give up myself or that is impossible to take away.
Some things are just not possible to follow through with. Parents say "we're never coming back" or "you're never going to get to do this again." Generally, I think it is best to keep never or always out of any conversation with kids. If you say you are never going to bring them to the park again, you better be ready to keep them away from all parks. Not following through speaks loudly to our children. You may think that you are punishing them in the moment, but in the long run, when you end up back at a park after promising never to return, you loose the power of your promises.
Other things we don't want to give up. Weekends with Grandma or playdates where we get some time to ourselves or time with other moms are things that benefit us. If these become threats for discipline, then you are punishing yourself too. There are times when these things can be leveraged but if you do it all the time, you are not really encouraging your child to behave. Once they have lost something they were looking forward to, the behavior can become worse because now they have nothing to loose.
The key is to think before you threat. Is this even possible? Do I really want to give up my weekend without kids? Threats never work if you don't follow through.