He just bought a house, so he's been strapped for cash lately.
Tips
memory
Literally 'hand-end tight' — 手头 (shǒutóu) means 'on hand / in one's possession', and 紧 (jǐn) means 'tight'. When the cash 'in your hand' is 'tight', you're broke. The opposite is 手头宽裕 (shǒutóu kuānyù, comfortably off).
register
Conversational and self-deprecating, perfect for politely declining to pay or to spend. Not an emergency — someone in real financial trouble would say 没钱 (méi qián) or 经济困难 (jīngjì kùnnan).
