specifically with the straw flip lip
Do these leak in bags? Don't trust my 4 year old to be able to swap it for the screw top lid when it goes in his bag and don't trust the teachers to make sure it's upright in the drinks part of his bag as it's faffy and easier for them to just Chuck it in the main bit which it always is.. so want to make sure it won't leak all over everything!!
It says it's leakproof but only with the screw top lid but wondered what people's experiences were