DS giggling when being told off

[wellsie]

Hello
Over the past few weeks DS has started to get the giggles when being told off.
He knows what he is doing is wrong and even covers his mouth and looks away to try and stop himself but he can't. On occassion I have had to walk away because I start to get the giggles .
Not sure how to handle this. Should I ignore and hope he stops it or is there something else we can do.
He started school this year and wondering if this is a nervous thing or something he is copying?
Any advice would be great.
Thanks
Wellsie

we have the same from DS (5) when he gets told off at the dinner table. it drives DH mad! it doesn't happen when he's on his own and being told off, but it's when his sis (7) is there, right beside him at the table - they glance at each other and set each other off. it is bloody infuriating!! he gets short shrift for it and can end up in his room mid-meal. am hoping it is YET ANOTHER phase !