For show
Definition 1 of 1
Pro Tip 1/3Attention Seeking
The phrase indicates an action done to get noticed, not for genuine reasons. 
His loud laughter was just for show to get everyone's attention.
Pro Tip 2/3Not Functional
Used to describe objects that look good but aren't really useful or used. 
The fireplace in their home is just for show; it doesn't work.
Pro Tip 3/3Hidden Sincerity
Reflects a lack of sincerity in actions, suggesting they're done to deceive. 
She pretends to care, but her concern is all for show.