Jackoff of all trades
A person who brags about knowing everything, but can't even tie their shoes right. They're like a kid who thinks they're Einstein, but they flunked math.
'He claimed he could do your taxes, your laundry, and your job interview. Now you’re out of work, your clothes are a mess, and you’re confused.'
'She said she could paint, sing, and dance. Now her painting looks like a toddler threw spaghetti at it.'
'He told me he could fix the roof, the TV, and my relationship. Now I’m living in a leaky house, watching static, and divorced.'