  In this note, we prove several Tur\'an-type results on geometric hypergraphs.
The two main theorems are 1) Every $n$-vertex geometric 3-hypergraph in 2-space
with no three strongly crossing edges has at most $O(n^2)$ edges, 2) Every
$n$-vertex geometric 3-hypergraph in 3-space with no two disjoint edges has at
most $O(n^2)$ edges. These results support two conjectures that were raised by
Dey and Pach, and by Akiyama and Alon.
