Lay it on with a trowel
Definition 1 of 1
Pro Tip 1/3Informal Use
The phrase is casual and not suitable for formal writing or speeches. 
When chatting with friends, you might say, 'She really laid it on with a trowel about her vacation.'
Pro Tip 2/3Negative Connotation
The phrase usually implies criticism and suggests someone is being deceitful or insincere. 
After the speech, Lena whispered, 'He was laying it on with a trowel, wasn't he?'
Pro Tip 3/3Visual Imagery
Imagine applying plaster with a trowel; this phrase evokes applying too much, thus 'overdoing' something. 
To portray the actor's bad performance, you might say, 'He laid it on with a trowel in every scene.'