faceplam
When you slap your face so hard your hand slips off and you end up head-desking or face-tableing like a total idiot.
'I faceplammed so hard my hand slipped and I head-desked the table.'
'He faceplammed and his hand slipped off, hitting the desk like a brick.'
'I faceplammed, my hand slipped, and I knocked my coffee all over my laptop.'