1.
If something doubles you up , or if you double up , you bend your body quickly or violently, for example because you are laughing a lot or because you are feeling a lot of pain.
...a savage blow in the crutch which doubled him up...
They laugh so hard they double up with laughter.
PHRASAL VERB : V n P , V P with/in n
• double over
Double over means the same as double up .
Everyone was doubled over in laughter.
PHRASAL VERB : V-ed P
2.
see also double 11